If these things were harmful to your baby, then the doctors wouldnt do it right? Antibiotics are safe when taken properly and have no bad or long term effect on you or your baby and as for pain killers certain kinds are dangerous but since your doctors know your pregnant they will elect to give you the safest one and will suggest it "as needed" dont worry it will be fine. it's not like you are abusing drugs or something. this is a one time thing and you and your baby will come out like champs. Good luck, I know all will turn out perfect for you.
I'm not sure I mean if your Dr assures you it will be ok then I'd have to go with his opinion. Good luck and hope all turns out good.