Pregnancy scare

So lately I just had sex with my boyfriend without a condom. He told me he almost came in me but he’s 100% positive that he didn’t. It’s been a week and day since we did it. Ive been on birth control for sometime now. Although, recently I’ve been put on a different birth control. I am still scared I am pregnant. But I get stomach cramps and my stomach kind of burns as well for the past days.