In January I hurt by back and butt really bad due to a fall. With a snow sled. I was in extreme pain for a few weeks. This was the day after I stopped my period, January 5th. I still have not gotten my period for February making me 14 days late. I have not been stressed or sick or any of the other issues that cause you to be late. This injury is all I can think of. Can thus be the case? I have had 5 negative tests.