I take the pill, have unprotected sex very often and sometimes miss or take late my bc. i've been getting real bad cramps lately. what could it be?

STD/STI or UTI: In one sense, by taking birth control pill, you're protected from pregnancy. However, need to take as directed (approximately same time daily). One pill at 11:59pm and next at 12:01am doesn't count. However, birth control pills don't prevent or lower risk for sexually transmitted diseases/infections. That's why also need to make male partner wear a condom each & every time. Also think uti. See doc.