gamgineun geoui naassneunde jaechaegiga gyesok nago miyeoldo isseo.

This is a very common learner question.

• 감기는 uses 는 because 감기 is being set up as the topic: as for the cold...
• 재채기가 uses 가 because 재채기 is the subject of the next idea: the sneezing is what is continuing/happening.

So the flow is roughly:

• 감기는 거의 나았는데 = as for the cold, it has almost gotten better
• 재채기가 계속 나고 = but sneezing keeps happening

Using 는 for 감기 makes it feel like the speaker is talking about the overall illness, while 가 with 재채기 highlights that sneezing is the symptom currently occurring.

거의 means almost or nearly.

So 감기는 거의 나았는데 means the cold is almost better or has almost gone away.

It softens the statement a little: the speaker is not saying they are fully recovered, only that they are close.

No. This is an important distinction.

There are two different verbs here:

1. 낫다 = to get better, recover

   • 나았는데 comes from this verb

2. 나다 = to come out, occur, happen

   • 재채기가 나고 comes from this verb

So even though they look similar in the sentence, they are different words.

Breakdown

• 낫다 → 나았다 / 나았-
• 나다 → 나고

This is a classic source of confusion for learners:

• 병이 낫다 = an illness gets better
• 재채기가 나다 = a sneeze comes out / you sneeze

This happens because 낫다 is a ㅅ-irregular verb.

When the ㅅ comes before a vowel, it drops out.

So:

• dictionary form: 낫다
• stem: 낫-
• add -았-
• the ㅅ drops: 나았-
• then add -는데
• final form: 나았는데

So 나았는데 is the natural conjugated form of 낫다.

Here -는데 gives a sense of:

• background information
• mild contrast
• leading into another related point

In this sentence, it works like:

• The cold has almost gotten better, but...
• The cold is almost better, however...

It is softer and more conversational than using a separate 하지만.

So 감기는 거의 나았는데 sets up the situation, and the speaker then adds the problem that remains: 재채기가 계속 나고 미열도 있어.

Korean often describes bodily reactions and symptoms with 나다, meaning something like to come out or to occur.

So:

• 재채기가 나다 = sneezing happens / a sneeze comes out
• 기침이 나다 = coughing happens / a cough comes out

This is very natural Korean.

There is also 재채기를 하다, which can mean to sneeze, but 재채기가 나다 sounds very natural when talking about symptoms or involuntary physical reactions.

So in this sentence, 재채기가 계속 나고 means sneezing keeps happening.

• 계속 means continuously, continually, or keep on
• -고 links one clause to the next, usually meaning and

So:

• 재채기가 계속 나고 = sneezing keeps happening, and...
• then the speaker adds another symptom:
  • 미열도 있어 = there is also a low fever

This makes the sentence feel like a natural list of continuing symptoms.

미열 means a slight fever or a low-grade fever.

도 means also, too, or as well.

So:

• 미열도 있어 = there is also a slight fever / I also have a slight fever

The 도 shows that this is an additional symptom, on top of the sneezing.

Without 도, it would simply state the fever. With 도, it emphasizes this too.

Because Korean very often omits subjects and possessives when they are clear from context.

In a sentence about symptoms, the listener naturally understands that the speaker is talking about themselves unless something else is specified.

So Korean does not need to say:

• 나는
• 내가
• 내 감기
• 내 재채기

The context already tells us that these are the speaker’s symptoms.

This is one of the biggest differences from English: Korean frequently leaves out information that English normally says explicitly.

It is casual / informal polite-neutral conversation, mainly because it ends in 있어 instead of a more formal form.

Compare:

• 감기는 거의 나았는데 재채기가 계속 나고 미열도 있어.
  casual, natural in conversation

• 감기는 거의 나았는데 재채기가 계속 나고 미열도 있어요.
  polite everyday speech

• 감기는 거의 나았는데 재채기가 계속 나고 미열도 있습니다.
  more formal

So the version you have sounds like something you would say to a friend, family member, or someone you speak casually with.