A médica disse que a dor vai passar, mas preciso dormir mais.

A médica uses the definite article a (“the”), implying a specific doctor known in context (e.g., my doctor, the doctor I saw).
If you said uma médica, it would mean “a (some/unspecified) doctor,” introducing her as new or not identifiable.

In Portuguese, many professions agree with the person’s gender. Médica is the feminine form, so it indicates the doctor is a woman.
O médico would be a male doctor. (In real life, you may also hear mixed usage depending on region/style, but médica is standard for a female doctor.)

Portuguese typically uses que to introduce a subordinate clause after verbs like dizer, achar, pensar, etc.
So disse que a dor vai passar = “said that the pain will pass.”
In English, “that” is often optional; in Portuguese, que is much more commonly required.

Vai passar literally means “is going to pass,” from ir (vai) + infinitive passar. It’s a very common way to express the near future or a strong expectation:

• A dor vai passar. = “The pain will go away / will pass.”

Portuguese also has a simple future (passará), but in everyday Brazilian Portuguese, vai passar is often more natural.

Here passar means “to pass/go away/stop,” as in a symptom ending:

• A dor vai passar. = “The pain will go away.”

Passar is very flexible and can also mean “to pass (a test),” “to pass by,” “to spend (time),” “to put/spread (butter),” etc.—context decides.

Portuguese often uses an article where English might not:

• a dor = “the pain” (the specific pain you’re feeling)

You can see dor without an article in some set expressions, but with a specific, discussed pain, a dor is very normal.

Mas means “but” and introduces contrast:

• The doctor says the pain will go away (good news),
• mas the speaker says they need to sleep more (a remaining issue/need).

Portuguese often drops subject pronouns because the verb form already signals the subject:

• preciso = “I need” (1st person singular)

Adding eu is possible, but it adds emphasis/contrast:

• Eu preciso dormir mais. = “I need to sleep more (me, specifically).”

Here it’s the verb precisar conjugated: (eu) preciso = “I need.”
Portuguese preciso can also be an adjective meaning “precise/accurate,” but the structure preciso + infinitive signals the verb:

• Preciso dormir. = “I need to sleep.”

After precisar (“to need”), Portuguese commonly uses an infinitive to say what you need to do:

• Preciso dormir. = “I need to sleep.”
• Preciso estudar. = “I need to study.”

You can also use precisar de + noun:

• Preciso de descanso. = “I need rest.”

Mais means “more.” In preciso dormir mais, it modifies dormir: “sleep more.”
Common placements:

• Preciso dormir mais. (most common)
• Preciso mais de dormir. (less common; sounds more marked/emphatic)

Usually it means more hours / more sleep in general. If you needed “more often,” you’d likely clarify with something like com mais frequência, but context normally makes dormir mais clear.

In Portuguese (as in English), it’s standard to use a comma before mas when it links two clauses:

• A médica disse que..., mas preciso...

It helps mark the contrast and separates the two parts.

Yes. Using direct speech with a colon and quotes is possible:

• A médica disse: A dor vai passar, mas preciso dormir mais.

But be careful: if you keep mas preciso dormir mais inside the quote, it sounds like the doctor is the one who needs to sleep more. If the speaker needs to sleep more, it’s clearer to keep only the doctor’s words in the quote:

• A médica disse: “A dor vai passar”, mas eu preciso dormir mais.

(Or keep the original indirect speech, which is already clear.)

In this sentence, it reads as the speaker’s statement: “but I need to sleep more.” The change from reporting the doctor (disse que...) to preciso (1st person) signals that shift.

If you wanted it to clearly be the doctor’s advice, you’d usually say:

• A médica disse que eu preciso dormir mais. (The doctor said that I need to sleep more.)
• A médica disse pra eu dormir mais. (Very common in Brazil: “The doctor told me to sleep more.”)

• A dor passa. = “The pain goes away” (general/habitual or present statement; can sound like a general truth)
• A dor vai passar. = “The pain will go away” (future expectation about this situation)

For reassurance about a current pain, vai passar is often the natural choice.