uisaga jeungsangeul deutdeoni yeori jogeum issdago haesseo.

의사가 uses the subject marker -가, which simply identifies the doctor as the subject of the sentence.

If you said 의사는, that would add more of a topic/contrast feeling, like:

• As for the doctor, after listening to the symptoms, he said...

In this sentence, 의사가 sounds natural because the speaker is just reporting what happened, without emphasizing contrast.

증상 means symptoms, and -을 is the object marker.

So 증상을 듣다 literally means to listen to the symptoms. In more natural English, that usually becomes something like:

• listen to the patient's symptoms
• hear about the symptoms

Korean often uses 듣다 with things like explanations, stories, worries, symptoms, etc.

듣더니 comes from 듣다 + -더니.

Here, -더니 connects two actions and often means:

• after doing/seeing X, then...
• when/after X happened, Y followed

So 증상을 듣더니 means:

• after listening to the symptoms
• once he heard the symptoms, ...

In this sentence, it shows that the doctor's statement came after hearing the symptoms.

Good question. All of these can connect actions, but they feel different.

• -고: simple listing/sequence
  
  • 증상을 듣고 말했다 = He listened to the symptoms and said...
• -아서/-어서: often gives a cause or natural sequence
  
  • 증상을 들어서 말했다 can sound like because/after he heard the symptoms, he said...
• -더니: often highlights that the speaker observed the first situation and then noticed the second result/action

So 듣더니 gives a slightly more vivid "then/after that" feeling. It can sound like:

• He listened to the symptoms, and then he said...

This is the quoted content of what the doctor said.

Breakdown:

• 열이 있다 = to have a fever
• 열이 조금 있다 = to have a slight fever / to have a little fever
• 열이 조금 있다고 = that there was a slight fever

The -고 here is not the connector and. It is part of the quoting form -다고, used in indirect speech.

So:

• 열이 조금 있다고 했어 = (He) said that there was a slight fever

Because 있다 does not take a direct object here.

In Korean, many expressions with 있다 use -이/가:

• 문제가 있다 = there is a problem
• 시간이 있다 = there is time / one has time
• 열이 있다 = one has a fever

So 열이 있다 is the normal Korean expression for to have a fever.

Because this is indirect speech.

• 있다고 했어 = said that there was...
• Direct quote would look more like:
  "열이 조금 있어요"라고 했어 = He said, "You have a slight fever."

Indirect speech is very common in Korean, especially in everyday storytelling. It sounds natural and efficient here.

했어 is the informal casual form.

That means the speaker is talking:

• to a friend,
• to someone younger,
• or in a casual narrative style.

More polite versions would be:

• 했다고 했어요
• or the whole sentence could become:
  의사가 증상을 듣더니 열이 조금 있다고 했어요.

So the sentence as written is casual, but not rude in the right context.

The person with the fever is not explicitly named, but it is understood to be the patient—the person whose symptoms the doctor listened to.

So Korean leaves it unstated because the context makes it obvious:

• The doctor listened to the symptoms
• Then said there was a slight fever

English often makes the subject clearer, but Korean often omits it when it is understood.

In this sentence, 조금 most naturally means a little / slightly.

So 열이 조금 있다 is best understood as:

• There is a slight fever
• You have a bit of a fever
• You have a mild fever

It softens the statement and makes it sound less severe than just 열이 있다.

Yes. The sentence has a natural storytelling flow:

• 의사가 증상을 듣더니 = the doctor listened to the symptoms first
• 열이 조금 있다고 했어 = then gave his assessment

Because of -더니, it feels like the speaker is recounting the doctor's reaction in sequence:

• The doctor heard the symptoms and then said there was a slight fever.

It sounds like a normal spoken retelling of a medical visit.