Here is how things go, I have not had a period in three and half months and I have taken two pregnancy test a month and then had a blood test done and all of them came out negative. Me and my spouse have been having unprotected sex for about 5months now and can not get pregnant but I was wondering why I haven't had a period and starting to have lower back pains and just been sick for like a month but I do not know what to do.