rare yellow brown stinky dischage

i am on the birth control shot. i've been on it since sep 22. i have had sex when two different guys; one on feb 28 and the other on march 25. i got a bladder infection after both times. the first time i drank cran berry juice and the infection went away. the second time i got these pills called cystex, the infection went away but a week or so later i noticed a rare discarge that i've never had before. i still have it right now except it got wose. first it was dark yellow and A LOT came out in my sleep. it had a very bad smell so i've been wearing tampons. now, it's slighty brown (still yellow) and theres a little blood in the discharge also. PLEASE tell me whats going on. i'm going to the doctor soon but i'd like to know before hand.