Confused

So, my boyfriend and I had unprotected sex last Thursday (he never came inside me before) but it was different this time, I was on him and he told me to get off and we were both shocked because he came, but we weren’t sure if he did it inside of me... We agreed that I should take plan B pill just to be sure. I took the pill on Friday. Everything was normal until Tuesday. When I got my period, again... I already got my period this month (first week) and now again?! It’s not very heavy but I experienced some light cramps... Should I be worried? 😫