Suggest Treatment For Painful Blisters That Comes After Excercise

im 18 yrs old and very healthy weight 150 pounds and dont get sick much. I havent hade sex i two yrs. anyhow everytime i exercise i get this painful blister in the very same spot the first time i had it i dealt with it for a week and it broke on its own weent it did it oozed brown and now that I got it again about several months later i dont know what to do its very painful to sit stand and walk please i need help i have no money for anitibiotics or to even go see a doctor. what do i do?