Scared...

I don't know if this is a birth control problem.. I'm really hoping it is. So lately I've been having brown blood, I wouldn't call it discharge cause it doesn't seem like it has the consistency of it its not like it's my regular period just spotting .. I'm on the pill and I started my brand new pack the 25 of September, before I got it, due to money issues I had to wait two weeks after my period ended to get the new pack (the one I started the 25th) on the two week period of not having it i had sex unprotected but he pulled out and I know there's always a possibility of getting pregnant, after that the most recent sex I had was two Wednesdays ago and he didn't come in me then either and I was on my pills. I'm freaking out about the bleeding and trying not to self diagnose from reading online, the blood has been consistent for two weeks now, and some sites say with birth control if you mess up the balance something like this could happen. Has anyone had similar experiences? And if not can you give me some advice please