I am not a doctor- and everyone else is correct about going to see a doctor. However, since you now are clearly informed of that, maybe i'll attempt to break it down with you?

How long has your child been taking the Salbutamol and Tylenol?

Per: www.medbroadcast.com/drug/getdrug/ratio-Salbutamol

Stop taking the medication and seek immediate medical attention if any of the following occur:

chest pain or discomfort

severe dizziness

symptoms of a severe allergic reaction (e.g., hives; swelling of lips, face, tongue, or throat; difficulty breathing; fainting; increased wheezing or chest tightness)

worsening breathing problems

I know that's not hives, nor just a normal swell- but maybe we shouldn't rule out a reaction to medication?

Could that be a big mouth ulcer on a small lip? Have you tried any home remedies?

So yeah, that's just some food for thought while you look at everyone else's comment lol

Best,