3 yo was on augmentin (amoxicillin and clavulanate) for ear inf 3 weeks later got strep throat now takes cefdinir will he always need strong antibiotics now or can take amox again?

Yes: It is common to treat with a broad spectrum med if a kid with strep had a penicillin drug within a month. The idea is that existing germs were not removed so different would likely work better. After a month or two, the germs in/on the body have changed out multiple times and the simple works again. You don't get "resistant" to simple antibiotics as a person, some germs do.

Amoxicillin : Amoxicillin may be used as indicated in the future.