Nie net die koors nie, maar ook die pyn maak haar moeg.

It is the Afrikaans equivalent of not only ... but also ....

So:

• Nie net die koors nie = not only the fever
• maar ook die pyn = but also the pain

The sentence is emphasizing that both things are making her tired, not just one of them.

This is a fixed Afrikaans pattern:

• nie net ... nie, maar ook ...

Even though nie is often part of normal negation in Afrikaans, here the whole expression works as a set phrase meaning not only ... but also ....

So you should learn it as one chunk:

• nie net X nie, maar ook Y

It does not mean the sentence is fully negative. It is an emphatic comparison structure.

No. The overall meaning is not negative.

It does not mean that the fever is not making her tired. Instead, it means:

• It is not only the fever; the pain too is making her tired.

So the point is addition and emphasis, not negation.

Because each noun has its own article.

Afrikaans, like English, normally keeps the article with each noun phrase:

• die koors = the fever
• die pyn = the pain

So when two noun phrases are linked in this structure, each one still keeps die.

Because that whole part functions as the subject of the sentence.

Afrikaans main clauses normally place the finite verb early in the clause, but the full subject here is quite long:

• Nie net die koors nie, maar ook die pyn = the full subject
• maak = verb
• haar moeg = rest of the predicate

So the structure is basically:

• [Subject] maak [object + complement]

That is why maak comes after both parts of the not only ... but also ... phrase.

Literally, it means makes her tired.

This is a very common Afrikaans pattern:

• maak + object + adjective

Examples:

• Dit maak my bly. = It makes me happy.
• Dit maak hom kwaad. = It makes him angry.
• Die pyn maak haar moeg. = The pain makes her tired.

So moeg is an adjective meaning tired, and maak causes that state.

Because haar is the object form, while sy is the subject form.

Compare:

• Sy is moeg. = She is tired.
• Die pyn maak haar moeg. = The pain makes her tired.

Here, her is receiving the action/effect, so Afrikaans uses haar.

Not always. It depends on how it is being used.

For example:

• Sy het koors. = She has a fever.
  Here koors is used without die.

But in your sentence, die koors refers to the fever as a specific thing affecting her, so the article is natural.

This is similar to English, where sometimes you say fever, and sometimes the fever, depending on context.

Not perfectly. A very literal breakdown would be:

• Nie net die koors nie = not just the fever
• maar ook die pyn = but also the pain
• maak haar moeg = makes her tired

That gets you close, but the most natural English translation is:

• Not only the fever, but also the pain makes her tired.

Depending on style, English often prefers:

• Not only the fever but also the pain is making her tired.
• It’s not just the fever; the pain is making her tired too.

So the structure matches English fairly well, but natural translation may vary.

Yes. Nie net ... nie, maar ook ... is very common, but you may also see alternatives such as:

• nie alleen ... nie, maar ook ...
• nie slegs ... nie, maar ook ...

These mean roughly the same thing, but nie net ... nie, maar ook ... is very natural and common in everyday Afrikaans.

Yes, that is a good idea.

Treat this as a set structure:

• nie net X nie, maar ook Y

Once you know that pattern, you can use it with many kinds of words:

• Nie net die koors nie, maar ook die pyn ...
• Nie net hy nie, maar ook sy ...
• Nie net vandag nie, maar ook môre ...

That will help you sound much more natural than trying to build it from English word by word.