Male adolescent, scratchy throat, drainage from nasal down back of throat, physician's assistant said it was allergy and then prescribed amoxicillan -- this doesn't sound right to me. maybe it is allergy, but amoxicillan is not for allergies, right?

Correct: Some trainees, lower level providers & some docs do this as personal insurance. They don't want to miss something that may come up in a day or two & have a mad patient complain to their clinic boss that they missed something. It happens less when you see the same provider over time & establish a trust that they will only treat what is found. Take it or not, it is confusing but might be needed.