Pregnant or just birth control pill?

Hi ive been on the pill two weeks and two days now....the week i first started taking the pill after 8 days i have unprotected sex and he did not *** in me but there is always a possiblity for pre ***. Then during the second week i had sex again but this time with a condom on but after he came when pulling the condom out a little bit of it was coming out. well this is the second day of my third week taking the pill....today randomly while in the store below my stomach i started feeling pain (pain i could handle) and that was about 3 hrs ago and its still here as well as back pain....is not unbearable but its pain....is this because i may be pregnant or because of the pill? btw i started the pill the day of my period and my period lasted two weeks (not normal for me). And yes both the times i had sex i was on my period...sometimes it was light and sometimes not...do you think im pregnant...have an infection? or is it a symptom of the pill once u start taking it? thank you!