Diarrhea and the pill

I started taking the pill 3 days after my period started, and I had sex without a condom after taking 11 pills. This is more than seven days, so I think I was protected. I did have some mild diarrhea one morning a few days into taking the pill, probably 10-12 hours after taking the pill (I take my pills at night). Should I be concerned that the pills weren't effective?