Hi, so my period is now almost 20 days late, I am NOT pregnant, I even checked just to make sure. I have had severe lower abdominal pain and diarrhea for about a month. I m tired alot more than usual, dizzy, I can t bend down to pick anything up without almost blacking out. I have been getting headaches, nausea, loss of appetite. What could be wrong? Should I see a doctor or wait it out? Also my back has been incredibly sore.