Pregnant?

I am currently on Alesse 28 for birth control. I have been taking the pill since late January early February. I have never missed a period or had any irregular periods. The last day of my last menstral cycle was on Thursday, September 14, 2006. I haven't felt great for the past three to four weeks experiencing headaches, upset stomach and loose bowel movements. I didn't think anything of it b/c I thought I just had a bug or something. This Wednesday, 9/20/06, I started bleeding again. It wasn't like a normal period. It was brownish/red and thick, almost like mucos. I am very concerned and I was wondering if, by the information I have given you, you could tell what is going on. I am always right on time with my period. Never early, never late. My breast are slightly sore and I have been experiencing slight cramping in my lower abdomen. Anything that you can tell me is much appreciated! Thank you!!