PLEASE HELP BROWN STUFF???

Hello im a 16 year old who is sexually active and im on Minastrin, 
Ive been having this brown slime come out of my you know what (SO GROSS) !!! For the past maybe 2 weeks. Ive been taking my pill daily and I have not skipped days. WHY IS THIS HAPPENEING. Has someone else experianced this?!?! HELP!!