What Is The Reason For Abnormal Periods After Partially Protected Sex?

iam a 22 girl , my period is unstable , the last month my period was perfect timing . but the next one should have occur at 25th of november, but it didnt come even on 26th when unfortunatly i was cuddeling with my fiance and he placed his *** on to mine and put it for maximum 1 cm as iam still a virgin after we finished in about 3 hours i started to bleed alot until 29 i stopped bleeding ( it wasnt my period though i think it is the hymen) . after that at 2 december i got my period and i bled too much and alot for 3 days ! but it stopped on the end of the third day although my normal period is for 5-6 days , i think its bcz of the stress since my fiance is travelling and i cried alot !and after it stopped am witnessing pain same like the periods pain but without any blood! im so confused