My Best Friend is 10 days late for her period and we got a test and it was negative , but it did the same thing to me before I found out because I was to early to find out . But her and her boyfriend were having sex and she got a real sharp pain in her lower stomach and couldn't move or anything afterwards , she tried soaking in warm water to see if it would help , but it didn't , could anyone tell me what this is ? Could she be pregnant , I should know , but that didn't happen to me before I found out .