How can I show my son I care about him when I ask a pharmacist for acne medicine in a public pharmacy? He got very angry.

Let go. Part of growing up is becoming independent, and you can encourage this. One minute a teen will beg you for help; the next, he will resent what you perceive to be simple nurturing. Anything having to do with his emerging sexuality is super-sensitive. Instead, offer him a physician office visit (if he wants) without you in the room. It'll help him become a man, and your family a happier one.