I took the 7th pill in my pack about 15 hours late. That night I had unprotected sex with my boyfriend(took the pill when I got home in the morning when i usually take it at 9 pm). In the middle of the week on my second week in the pack, I bled(brown with clots) for a day. I've been on the pill for 3 years and have never break through bled. I'm worried it was implantation bleeding or something is wrong. I took a pregnancy test and it came up negative but it could have just been too early. I'm worried something is wrong with me or my pill. Any advice or similar experiences?