Help help help

Okay so my boyfriend and I were in the shower today and decided we were going to try something 
So we decided to try anal, it was going good until he slipped and his dick went near the entrance of my vagina, I had a tampon in though. Is there a possibility any pre cum got inside me? After that happened I washed very thouroughly. I know this may sound extremely dumb but I'm just worried as I just finished my period