La médica dijo que la niña no debía rascarse porque la picadura podía empeorar.

Médica is the feminine form of médico, so it matches a female doctor.

The article la is used because here the word is not just naming a profession in general; it means the doctor, a specific person in the story. Compare:

• Es médica = She is a doctor.
• La médica dijo... = The doctor said...

In modern Spanish, especially in Spain, la médica is standard and very common for a woman.

After decir when you report what someone said, Spanish normally uses que to introduce the reported clause.

So:

• dijo que... = said that...

This is very common in indirect speech:

• Dijo que venía = She said that she was coming.
• Dijo que la niña no debía rascarse = She said that the girl shouldn’t scratch herself.

English often drops that, but Spanish normally keeps que.

The sentence is reporting the doctor’s words, not giving her exact words directly.

So La médica dijo que la niña no debía rascarse is an indirect way of reporting the message.

A more direct version might be something like:

• No te rasques if the doctor was speaking directly to the girl
• Que no se rasque if the doctor was telling someone else about the girl

Spanish often uses indirect speech like this when narrating events.

Debía is the imperfect of deber, and here it fits a reported obligation from the past.

• debe = present: she should / must
• debía = past viewpoint: she should / was supposed to
• debió can mean something different depending on context, often she must have... or she should have...

So no debía rascarse means something like:

• she shouldn’t scratch herself
• she wasn’t supposed to scratch herself

The imperfect sounds natural because the doctor is giving advice or obligation in the past narrative.

Rascar means to scratch something or someone.

Rascarse means to scratch oneself.

That se shows that the action is done to the same person who performs it. So:

• rascar = to scratch
• rascarse = to scratch oneself

In this sentence, the girl is the one doing the scratching and also the one affected by it, so the reflexive form is used.

Yes. With a conjugated verb plus an infinitive, the reflexive pronoun can often go in either place:

• la niña no debía rascarse
• la niña no se debía rascar

Both are grammatical.

The version with the pronoun attached to the infinitive, rascarse, is often felt to be a little cleaner and more straightforward here.

Because both refer to specific things already identified in the situation:

• la niña = the girl
• la picadura = the bite / sting

Spanish uses definite articles very naturally with specific nouns. In this sentence, we are not talking about just any girl or any bite, but a particular girl and a particular bite.

Picadura is a general word for a bite or sting, especially from an insect or similar creature.

Depending on context, it could be:

• a mosquito bite
• a spider bite
• a bee or wasp sting

Spanish often uses picadura as a broad term, and the exact English choice depends on what caused it.

Here podía is the imperfect of poder, and it expresses a past possibility or risk from the narrator’s point of view:

• podía empeorar = could get worse / might get worse

Why not the others?

• podría is conditional: could in a more hypothetical sense
• pudo is preterite: was able to or managed to, and it usually sounds more like a completed event

So podía is the best choice for an ongoing possibility in the past.

Because dijo que usually introduces a reported statement, and reported statements normally take the indicative, not the subjunctive.

So:

• dijo que la picadura podía empeorar is normal
• dijo que la niña no debía rascarse is also normal

The subjunctive is more likely if you report a command or request in a different way, for example:

• La médica dijo que la niña no se rascara

That version sounds more like the doctor said/told her not to scratch herself. By contrast, no debía rascarse presents it as advice, obligation, or recommendation.

Because empeorar can work intransitively, meaning to get worse.

So:

• La picadura podía empeorar = The bite could get worse

That is completely natural Spanish.

You may sometimes see reflexive forms like empeorarse, but in a sentence like this, plain empeorar is the most standard and natural choice.

It can be somewhere between the two, depending on context.

No debía rascarse often suggests:

• she shouldn’t scratch herself
• she wasn’t supposed to scratch herself

In medical advice, deber often sounds like a recommendation with some authority behind it. It is not always as strong as a strict must, but it is stronger than a casual suggestion.

So here it sounds like medically informed advice: scratching was not advisable because the bite could worsen.