Bleeding outside a regular menstruation has many causes, including implantation, and threatened abortion. To make a long story short, I advise that u do a pregnancy test, and, at the least, an ultrasound of ur pelvis( ovaries, uterus,etc..) . If they do not reveal any explanation for ur bleeding n cramps, like a tumor, fibroid or otherwise, then u go for hormonal blood tests, thyroid studies included. I believe this will solve ur issue. Best of luck.
Dr Hana Fayyad( Maria Jasmine Freeman)