Hello. I've been on birth control for four months now and everything has been working great. A couple of days ago I was put on Amoxicillin and a nasal spray because I have a sinus infection. I am on Sprintec birth control and I have no idea if these two medications will affect it. I also missed a pill a few days ago, but according to my birth control pamphlet one missed pill shouldn't affect anything. My boyfriend and I today were fooling around and he came, but a while afterwards we grinded naked. And his area was definitely touching mine, but no penetration. Should I be worried about pre cum or leftover cum? I am concerned and am wondering if I need to take plan B? Please help?