Really need some advice

So my period started on January 21 and it stopped on January 26. I had unprotected sex the day after that (yeah, I know. should have been protected.) and my boyfriend and I aren't sure if he came or not. I reached climax and then we thought he did, but I couldn't tell. My stomach has been feeling funny ever since but I have been taking that as stress about it. He says he didn't, and I believe him but I want to be 100% positive. What are the odds of me getting pregnant if he did reach climax inside of me?