I'm having lower back pains, nauseous a lot, stomach feels weird. Its been 6 days since I ended ovulation. I had unprotected sex twice during. Advice?

Observe. You probably had a corpus luteal (physiological ovulation) cyst that burst. These symptoms usually resolve in 2-3 days, however, if STD is a concern that get evaluated. Also, if your cycle is delayed , then do a pregnancy test. If pregnancy is not desirable then use consistent contraception.