I have been taking birth control for 2 months now and I started to get this brown discharge on the beginning of my 3rd week. It isn't a lot just enough to stain my undies. I'm sexually active and birth control is the only protection we use so I'm kinda scared I could be pregnant? I take my birth control every day at the same time so I'm not sure what's going on. The birth control is Tri Sprintec.