Sex after period? 🙃

Today well yesterday (Thursday) was the last day of my period cycle.. is what I thought since I hadn't been spotting or anything.. my BF and I ended up getting intimate. After we finished I went to the rr and I cleaned myself up nothing was wrong... a hour in a half later I go to the restroom and I'm bleeding again.. like a light reddish pinkish kinda blood.. and have cramps... so my question is can anything happen to me? I mean he didn't cum inside me or anything like that.. I just want to know why I'm bleeding/spotting again. Is it wrong to be intimate the same day your cycle has ended?  I feel so weird, my body is aching.. and like I said I hadn't done something like being intimate the same day of a ending cycle..😞😞😞😞