Can you get cramps and still be pregnant?

I'm 19. I'm on a BCP but i had unprotected and after that I missed 2 pills. After that i started taking them regularly. So Aunt Flo was supposed to come yesterday. I've been having lower back pain for a week now and I'm having some odd cramps that seem to go away when i lay down (which is not normal for me, when i get cramps there is no stopping it but with Motrin). P.S my are sore. Is this normal for pregnancy or am I just worring about it too much?