O mal-estar melhorou depois da hidratação, e me recuperei.

Mal-estar is a masculine noun in Portuguese, so it takes o in the singular: o mal-estar.

It is a fixed compound noun, and its gender is something you simply learn with the word. So:

• o mal-estar
• um mal-estar
• os mal-estares (plural)

Because mal-estar is a standard compound noun in Portuguese. The hyphen is part of the correct spelling.

This is similar to how some English compound words are written in a fixed way. You should learn mal-estar as one vocabulary item.

Melhorou is the pretérito perfeito (simple past / preterite) of melhorar.

Here it is third person singular because the subject is o mal-estar:

• o mal-estar melhorou = the discomfort improved / got better

It describes a completed change in the past.

Portuguese often uses melhorar where English uses get better or improve.

So:

• O mal-estar melhorou = The discomfort improved / got better

Using ser or estar with better in a direct word-for-word way would usually sound less natural here. Melhorar is the normal verb for this kind of improvement.

Da is a contraction of de + a:

• depois de = after
• a hidratação = the hydration
• de + a = da

So:

• depois da hidratação = after the hydration / more naturally, after hydration

This kind of contraction is very common in Portuguese.

Because Portuguese often uses the definite article where English might not.

So hidratação appears here as a hidratação, and after depois de, that becomes depois da hidratação.

In many contexts, leaving out the article would sound less natural. Portuguese uses articles more often than English does.

Using the noun hidratação makes the sentence sound a bit more medical or clinical.

It can suggest something like:

• hydration in general
• receiving fluids
• a medical intervention
• rehydration

If you wanted a more everyday phrasing, you might say something like:

• depois de beber água
• depois de me hidratar

So depois da hidratação has a slightly more formal or medical feel.

Because recuperar-se is commonly used as a reflexive verb meaning to recover.

So:

• recuperar = to recover something
• recuperar-se = to recover, to get better

Examples:

• Recuperei o dinheiro. = I recovered the money.
• Me recuperei. = I recovered / I got better.

Without me, the sentence would usually sound incomplete or would suggest you recovered something.

In Brazilian Portuguese, me recuperei is the normal and natural order.

• me recuperei = standard, natural in Brazil
• recuperei-me = grammatical, but formal/literary and unusual in everyday Brazilian speech

So for Brazilian Portuguese, me recuperei is the form learners should normally use.

Portuguese often omits subject pronouns when the verb already makes the subject clear.

Here, recuperei clearly shows first person singular:

• recuperei = I recovered

So eu is not necessary.

You could say eu me recuperei, but that would add emphasis, contrast, or clarity.

Yes. In the first clause, the subject is o mal-estar:

• O mal-estar melhorou

In the second clause, the subject is an implied eu:

• (eu) me recuperei

That kind of shift is normal as long as the meaning is clear. Portuguese often leaves the second subject unstated when the verb form already identifies it.

The comma helps separate two clauses, especially because the subject changes:

• clause 1: o mal-estar improved
• clause 2: I recovered

In Portuguese, commas before e are not always used, but they are more likely when:

• the subject changes
• the second clause adds a distinct idea
• the writer wants a clearer pause

So the comma is quite natural here.

Yes. Both are in the pretérito perfeito.

• melhorou = third person singular
• recuperei = first person singular

They both describe completed past events:

• the discomfort improved
• I recovered

They are related, but they focus on different things.

• O mal-estar melhorou focuses on the symptom/condition
• Me recuperei focuses on the person

So the sentence first says the unpleasant feeling got better, and then says the speaker recovered.

Using both gives a fuller picture than using just one.

Yes, you could.

• Melhorei depois da hidratação = I got better after the hydration.
• O mal-estar melhorou depois da hidratação, e me recuperei. = The discomfort improved after the hydration, and I recovered.

The version in your sentence is a bit more detailed because it separates:

1. the improvement of the symptom
2. the recovery of the speaker

So melhorei would be simpler, but the original sentence is perfectly natural too.