I keep breaking out on my chest kind of?

im 15 and well i went to the doctor with these abrasions on my chest it looks like a pimple but it hurts to touch and i can squeeze it but nothing comes out except sometimes it looks like water and then they become scars and its very embarring the doctor told me it was bacteria in my body coming through my hair follicles and he gave an antibiotic to take twice a day but i think im allergic to it and nothing happens when i take it but my freshman formal is right around the corner and i cant go with red spots all over my chest and neck is there anything i can do??? has anyone ever had a problem like this???