I have had my menstrual cycle every month except when I was
pregnant since I was 12 I am now 36 I had a tubal ligation when my last child was born in 2009. I have had a heavy cycle every month sometimes late but still every month. At the end of sept i had light brown discharge for the last 3 days of the month now I am having light but red menstraul blood. Not heavy at all like it normally is. I took 2 pregnancy tests and both were negative. What other causes are there to this?