What Causes A Scanty Period,abdominal Cramps And Tight Vagina?

hello i have missed my period for about a month now and my last one i did have was really light and i had no cramps which was weird now i have been having cramps and other pregnancy symptoms but i took tests and they were negative ..also my down there part has got tight like im a virgin again which is really weird and my pregnant friend has the same problem ..i dont know if you can help but i hope you can i have no insurance to go to a dr.