I imagine they would just continue your antibiotics 'till it was all cleared up if it wasn't better by the expected time. Also, if it was really painful to give you any kind of shot, that would only make it hard to give you, you know? Just like how the dentists numb things in your mouth because it would be kind of difficult to work on you if it hurt you, the doctors would probably do the same. They would probably numb it if they had to do anything.
I know how you feel with not wanting to talk to your mom about it. I never go to my parents for anything because they aren't helpful.
You're alright. :)