Ok, so I understand that pregnancy is different from person to person. My fertile window was the 3rd through the 9th. Me and my boyfriend had sex multiple times every day. Starting about 4-6 days ago I got bad lower back pain daily now. I also have cramps that are almost gone but have been off and on. The past 4 or 5 Days I've gotten sick from 2 to 5 in the morning and would go to sleep and wake up fine. Today I tried smoking a cigarette and it made me sick. Happened twice. Can anyone tell me what it could be? Thanks.