I've been on birth control pills for a month and five days. The first month I had diarrhea, twice, once each day but they were both ten hours after I took the pill. I think it might have been a side effect. But that was like two weeks into the first pack. I had diarrhea on thursday nine hours after taking my pill. This month it was a one time thing. All the times I had it, it wasn't severe, it was basically just one loose bowel movement. But on Friday, I had sex and the condom broke. This is the first time I have sex "without a condom." I'm very nervous I might get pregnant. I got the pill in case the condoms failed. Would the one loose bowel movement nine hours after taking my pill have cause the birth control pills to be less effective? (& sorry for all the extra info I doubt the two times I had it last month even matter, I got my period & took more the seven days of active pills passed after I had it last month. I'm just concerned about thursday.) Is Plan B necessary?