what do you think?

So I had unprotected sex a week before my period. It was 2 days late but I got it and thought I was in the clear but I only bled for like 3 days i normally go the whole week. Today while I was doing my job I noticed things that usually didn't make me sick I was gettin nauseous and my boobs are kinda sore which normally happens before I have my period and didn't this time. Do you think it's a delayed reaction or could I be pregnant?