oneureun gichimi simhago kosmuldo naseo byeongwone garyeogo hae.

은 marks 오늘 as the topic.

So 오늘은 gives a sense like:

• As for today
• Today, at least
• Speaking of today

In many cases, 오늘 by itself would also be possible, but 오늘은 can sound a little more natural when the speaker is setting today apart from other days. It can subtly imply something like today is different or today, in particular, I’m not feeling well.

Because 심하다 describes the cough as being severe, and in Korean that noun is marked as the subject of the descriptive verb.

So:

• 기침이 심하다 = the cough is severe

A learner might expect an object marker, but 심하다 works more like to be severe, not to severely do something.

So:

• 기침을 심하다 ❌
• 기침이 심하다 ✅

심하고 is 심하다 plus -고, which connects one clause to the next.

Breakdown:

• 심하다 = to be severe
• 심하-고 = is severe, and...

So 기침이 심하고 means:

• the cough is bad, and...
• I have a severe cough, and...

Here -고 simply links this symptom to the next one.

They do different jobs here.

• 기침이 심하고: -고 = simple connection, like and
• 콧물도 나서: -아서/-어서 = reason or cause, like because or so

So the flow is roughly:

• My cough is bad, and I also have a runny nose, so...
• Because of that, I’m going to the hospital

Korean often uses -고 to list facts, and then -아서/-어서 to connect those facts to the result.

도 means also or too.

So:

• 콧물이 나서 = because I have a runny nose
• 콧물도 나서 = because I also have a runny nose

It shows that the runny nose is an additional symptom, besides the severe cough.

In this sentence, 도 matches the earlier idea that there is already one problem:

• severe coughing
• also a runny nose

Yes, and that is exactly why it is used here.

In Korean, 나다 is very commonly used for symptoms or physical conditions that appear or come out.

Examples:

• 열이 나다 = to have a fever
• 땀이 나다 = to sweat
• 콧물이 나다 = to have a runny nose
• 기침이 나다 = to cough / to have a cough come out

So 콧물도 나서 is a very natural Korean way to say that a runny nose is occurring.

Even if it sounds a little different from English logic, it is standard Korean symptom vocabulary.

Because 가다 takes a destination with 에.

So:

• 병원에 가다 = to go to the hospital

병원을 가다 is not standard here because 병원 is not the object of the verb. It is the place you are going to.

Common pattern:

• 학교에 가다
• 집에 가다
• 회사에 가다

So 병원에 가려고 해 is correct.

-려고 하다 expresses intention or plan.

So 가려고 해 means:

• I’m planning to go
• I’m going to go
• I’m thinking of going

It is slightly different from a plain future statement. It focuses on the speaker’s intention.

Compare:

• 병원에 갈 거야 = I will go to the hospital
• 병원에 가려고 해 = I’m intending / planning to go to the hospital

In this sentence, 가려고 해 sounds natural because the speaker is explaining their current plan based on their symptoms.

해 is the casual, informal style.

So:

• 가려고 해 = casual
• 가려고 해요 = polite

The sentence as given sounds like something you would say to:

• a friend
• a family member
• someone younger
• someone you are close to

If you wanted a polite version, you could say:

• 오늘은 기침이 심하고 콧물도 나서 병원에 가려고 해요.

The meaning stays the same; only the speech level changes.

That is very normal in Korean.

Korean often puts:

1. background or reason first
2. main action at the end

So the structure is:

• Today, my cough is bad and I also have a runny nose, so...
• I’m planning to go to the hospital

This matches a very common Korean sentence pattern where the main verb comes last and earlier parts build up the context.

Yes. There are several natural alternatives, depending on nuance.

For example:

• 오늘은 기침이 심하고 콧물도 나서 병원에 가려고 해요.
  Same meaning, but polite.

• 오늘은 기침이 심하고 콧물도 나와서 병원에 가려고 해.
  Very similar; 나와서 may feel a bit more transparent to learners because it clearly shows the -아/어서 form from 나오다/나다-like behavior, though 나서 is the common natural form here.

• 오늘은 기침도 심하고 콧물도 나서 병원에 가려고 해.
  This puts 도 on 기침 too, making the list of symptoms feel more balanced.

The original sentence is already very natural. These are just small variations in style or emphasis.