Hi, I missed two of my monthly periods so I went to the doctor and he prescribed medicine to make me start my period, not only did it not start my period but I also missed another period.. And I m having all of the following: lower back pains, nausea and vomitting, tender breast , and my ribs feel like they re cracking. This has been going on for about two weeks... My boyfriend and I ARE trying to get pregnant, but I ve taken 3 tests and they ve all been negative. What s going on?