Problems with Seasonale?

I have been taking Seasonale for a year and 3 months now. Two weeks into my 5th pack I started getting brown spots, and and it worsened with a little occational red bleeding. It has been going on for almost two weeks now. Can anyone tell me a possible reason why this is happening?

My periods have only been between 3-6 days while on this pill, if that matters. It has helped with the cramping and everything else.

This happened after switching to the Generic brand, could that be why?I was on the 2nd month of the generic brand when it started