help!

I just started Microgestin birth control pill on September 25th, a week before my period was to start I started bleeding really light pink for two days then it stopped. Then the day before my period was to start it started brown blood for 3-4 day but very light and I'm now on my 8th day bleeding that has since gone from light color and stopped for a few hours between the days to back to dark red/brown with no clots like I normally have. Sorry if sounds gross but I'm haveing other pregnancy symptoms and I have had unprotected sex often. So what could this mean? Could this just be another period or is it possible I'm pregnant?