My period was from 11/9 to 11/11, but it was suppose to start 11/5. I've been on BC since May but just switched to Yaz in October. I haven't been taking them at the same time everyday and i've had to take 2 or 3 pills every time to make up the missed pills. I had unprotected sex on 11/19 and twice on 11/21. On Sunday, 11/23, I started to feel different. I felt like I had a mild case of the cramps and I felt like something was different in my lower region. I'm not due for my next period until 12/3. My boobs started to feel tender and hurt when water hit them in the shower. I've been cramping on and off for the last 5 days and i've had a mild case of diarrhea for the last few days as well. I've had headaches and lower back pain as well as slight nausea for the last couple days. Yesterday, I started what I think is my period, but it's a week early and it is different than normal. It isn't spotting, but it isn't extremely heavy either. It started off as a really dark brown and now it is a mixture of dark brown and dark red and There was a very large clot in my pad today. I'm very regular and never start a week early. I cramped really badly right before it started, but it disappeared once it started. Could I be pregnant and could the bleeding be implantation bleeding?