Implantation Cramps

When i ovulate i have cramps on my left side and they are not bad just a slight annoying pain. But the other night i was sleep and i had a really bad pain on my left side in which i couldn't really move all i could do was lay on my right side and hope it would go away. The previous day i was complaining to my husband saying that my lower back was hurting, and now i'm feeling nauseous. Me and my husband dont use condoms he pulls out but i know u can get pregnant with pre-cum so what do anybody think.