hi i am have lower back pain and i ahve me urinating more offten than usual, im last for my period, i have eating more than i usualy eat as well as eating things i would not normally eat, i have had chronic headaches but they are not so bad now, im not sleeping too well im waking up in the middle of the night and early hours of the morning with stomache pain or cramp but it stop opnce i have used the toilet, i have taken a pregnancy test and that came back negative.. what could it be ????