Constant pain in lower left abdomen for 5 years and getting worse.

I am 33. 5'1 and 220lbs. I was born with an AV Malformation (a seizure disorder). I've only ever had 2 seizures.  I take Tegretol 200mg 3x a day since I was 15. I am Native American and half Caucasian.  My family has a history of diabetes, stomach cancer, high blood pressure, heart disease, stroke.  My mother died of a heart attack as a complication of renal and heart failure when she was 56. I use to smoke from age 16 to 21.  I dont drink.
5 years ago I started to ride an excercise bike and gradually worked up to 1hr a day.  I lost 20lbs. I started to notice a slight ache in my lower left abdomen. I then had a dizzy vertigo experience a few nights later(This has never happened before). The pain has become so severe that I stopped exercising about 1 1/2 yrs. ago.  Other symptoms I have are: Dark circles under my eyes. My stool can go from bright yellow to black on the same day.  My period has become just light spotting, when I use to have long and heavy bleeding.  I now have twinges of pain in my lower right ab and in my lower back on the left. I feel lightheaded, tired and weak.  I feel worse and extremely tired in the evening.  Sometimes I feel as if I might pass out from being so tired.  After doing strenuous physical activity i've noticed pinprick size drops of blood in my bra. I've also had discharge from my navel that looked like and smelled like it had blood in it. I have pain that seems to start from my navel and spreads out leaving my navel area very sore.  I dont work, I dont have children, no pregnancy. Please, any help you can offer will be appreciated.