I haven't had a period since the middle of feb. 2013 last month I took a PT and it was negative but for the past two weeks Ive been having cramping with white discharge, ive been cleaning around the house and feeling light headed afterwards, ive been bending down and standing back up straight and feeling lightheaded afterwards, my nipples are sore and I have a little fatigue plus my lower back feeling sore, what could be going on?