I've been on YAZ for ~4 or 5 months now. Last month was my first without spotting. I thought all was well, but three days ago I didn't just start spotting... It's literally like a period. It's HEAVY and painful and I don't know why it's happening. I have 11 active pills left in my pack. I always take them on time and have never missed a pill, so I have no idea why this is happening. Is there an explanation for it?