Me and my boyfriend had sex on feb 24th & he came inside me ; lastnight I took a HPT & it came to be negative but I've been having serious back pains , nausea , something like cramps & exhaustion . Is there a chance that I AM pregnant?d

Any time you have sex there is ALWAYS some chance of pregnancy, especially with unprotected sex.it may be too early for a hpt to be accurate. I'd try again around the time you expect your next period using first morning urine.

If the pain is bad and not responding to your usual pain relievers you should call your doctor. Backaches and cramps are common with pms, nausea and exhaustion aren't unheard of either but if this isn't normal for you it may be more than just pms.

There is always a chance you can be pregnant with unprotected sex, I suggest you see a doctor. Have you missed your period yet?