syouzyou ga karukute mo, nagaku tuduku nara naika de mite moratta hou ga ii.

軽くても comes from 軽い meaning light / mild.

The pattern て-form + も means even if or even though.

So:

• 軽い → 軽くて
• 軽くても = even if it is mild / even though it is mild

In this sentence, 症状が軽くても means:

• even if the symptoms are mild

This is a very common pattern:

• 高くても買う = Even if it’s expensive, I’ll buy it
• 雨でも行く = Even if it rains, I’ll go

Here it sets up a contrast: mild symptoms are usually not too serious, but if they continue for a long time, you should still see a doctor.

が marks 症状 as the thing being described by 軽い.

So 症状が軽い means:

• the symptoms are mild

Using が here is very natural when introducing or describing the condition itself.

If you used は, it would sound more like you are contrasting the symptoms with something else:

• 症状は軽くても... = As for the symptoms, even if they’re mild...

That is possible in some contexts, but 症状が軽くても is the more neutral and direct phrasing here.

長く is the adverbial form of 長い.

Since 続く is a verb, you need the adverb form to describe how it continues.

• 長い = long
• 長く = for a long time / long

So:

• 長く続く = continue for a long time

This is a very common pattern with -i adjectives:

• 早い → 早く
• 遅い → 遅く
• 短い → 短く

続く means to continue / to last.

なら adds the meaning if it is the case that or if.

So:

• 長く続くなら = if it continues for a long time

In this sentence, なら sounds like conditional advice based on a situation:

• If that’s the case, then...

It is a very natural choice when giving recommendations.

All of these can express conditions, but they do not feel exactly the same.

• なら: if that’s the case / if it is true that
• たら: if/when that happens
• と: more automatic or general consequence

Here, なら fits well because the speaker is responding to a condition and giving advice:

• If the symptoms continue for a long time, then you should...

It feels a bit like: in that case.

If you said 長く続いたら, that would also be possible, but it sounds a bit more like waiting until that situation actually happens.
なら works nicely for general advice.

内科 means internal medicine.

In real-life usage, it can refer to:

• the internal medicine department in a hospital
• an internal medicine clinic
• a doctor who treats general medical problems that are not surgical

So in this sentence, it means something like:

• at an internal medicine clinic
• by an internal medicine doctor

Here, で marks the place where the action happens.

• 内科で診てもらう = to get examined at the internal medicine department/clinic

This is natural because the examination happens there.

If you use に, it usually marks a destination, target, or indirect object, so it would not fit as well in this structure.

Compare:

• 病院に行く = go to the hospital
• 病院で診てもらう = get examined at the hospital

So で is used because it marks the location of receiving the medical service.

診て is the て-form of 診る.

診る specifically means:

• to examine medically
• to see a patient

This is different from 見る, which is the general verb to see / to look at / to watch.

So:

• 映画を見る = watch a movie
• 患者を診る = examine a patient

In speech, みて sounds the same either way, but the kanji tells you which meaning it has.
Here, because it is about symptoms and internal medicine, 診る is the correct verb.

〜てもらう means to have someone do something for you or to receive the favor/service of someone doing something.

So:

• 診てもらう = to have someone examine you
• more naturally: to get examined

The person doing the examining is not directly named, but it is understood to be a doctor or medical professional.

This pattern is very common:

• 先生に教えてもらう = have the teacher teach you
• 友達に手伝ってもらう = have a friend help you

Here, it adds the sense of receiving medical care from someone.

This is a very common question.

The pattern 〜たほうがいい is the standard way to give advice:

• 行ったほうがいい = you should go
• 休んだほうがいい = you should rest
• 診てもらったほうがいい = you should get examined

Even though た is the past form, in this pattern it does not usually mean past time.
It is just how the advice pattern is formed.

So 診てもらったほうがいい means:

• it would be better to get examined
• you should get examined

This is much more natural than 診てもらうほうがいい in ordinary advice.

Literally, ほう means something like side or option.

So 〜たほうがいい is literally:

• the option of doing X is good

In natural English, that becomes:

• you should do X
• it’s better to do X

So:

• 診てもらったほうがいい literally = the option of having someone examine you is good
• natural meaning = you should get examined

Japanese often leaves out the subject or object when it is obvious from context.

In this sentence, the person being examined is understood to be:

• you
• or the person with those symptoms

So even though there is no explicit あなたは, the sentence naturally means something like:

• If your symptoms are mild but continue for a long time, you should get examined...

This kind of omission is extremely common in Japanese.

The comma is not grammatically required, but it helps readability.

It separates the condition:

• 症状が軽くても、長く続くなら...

This makes it easier to see the structure:

1. Even if the symptoms are mild
2. if they continue for a long time
3. you should get examined at internal medicine

Japanese punctuation is often more flexible than English punctuation, so the comma is mainly there to make the sentence easier to read.

It breaks down like this:

• 症状が軽くても
  = even if the symptoms are mild

• 長く続くなら
  = if they continue for a long time

• 内科で
  = at an internal medicine clinic / in internal medicine

• 診てもらったほうがいい
  = you should get examined

So the overall structure is:

• Even if A, if B, it is better to do C

More naturally:

• Even if the symptoms are mild, if they continue for a long time, you should get examined by an internal medicine doctor.

〜たほうがいい usually gives advice or a recommendation.

Its strength depends on context and tone:

• sometimes it is a gentle suggestion
• sometimes it can sound fairly strong, especially in health or safety contexts

In this sentence, because it is about symptoms lasting a long time, it sounds like sensible medical advice:

• you really should get checked

So it is stronger than a casual suggestion, but not as direct as a command.

Yes, 病院で診てもらったほうがいい would also be possible, but the nuance changes.

• 病院 = hospital
• 内科 = internal medicine department/clinic

Using 内科 is more specific. It tells you what kind of medical department is appropriate.

Using 病院 would be more general:

• You should get examined at a hospital

Using 内科 is more helpful if the speaker wants to suggest the right department for these symptoms.