White stuff on my tonsils from strep throat after taking antibiotic. What to do?

Normal finding. The tonsil tissue sheds over time like your regular skin. During and after infection there is more superficial tissue that needs to shed, and requires you that resume eating well. The mechanical action of swallowing will strip some of this heaped up debris. The more roughage you ingest the more tonsil cleaning it will do. Minimal appetite during an illness allows it to heap up.
Thrush? If there is also a white coating on your tongue- you could have oral thrush. Please advise your physician as this can be easily treated.