I bleed after exercising? what does that mean?

hi!! i'm 25 yrs old and i used to weigh 84 kg in december 2011..but now after extensive exercise i weigh 74 kg...i lost 20 pounds in 5 months by running and jogging,but then for the last 3 months i had periods for 20days each month and i also bleed after exercise... does any one knows wat this means ?? pls dont tell me to go see a doctor becoz i'll be seein one tomorow...so if any one has any expierience pls let me kno...