I switched my birth control from brand name to generic two months ago. Had my period and everything and I'm now on my third pack. So it should be working by now right? The last five days straight I've been spotting - first pink and watery, then brown and slimy discharge. I did have sex 6 days before it started and my period is due next week. Everything I'm reading says that it's implantation bleeding. Could that be possible?!