I think I have a bleeding stomach ulcer - how much blood does it take to change the colour BMs?

After some recent stressful situations, I've had some pretty bad stomach pains, and I've been having black/dark green stools for a day or so now, and I think I've had an ulcer before (but my doctor was a quack, and didn't do any check ups or tests to diagnose it). I'm curious to know how much blood you'd have to be loosing to change the colour of your bowel movements? (And yes, I do have a new doctor, and an appointment to check things out)I think I have a bleeding stomach ulcer - how much blood does it take to change the colour BMs?
By the time it is enough to consistently darken your BM's, it is enough to give you anemia.
Can you safely take Pepcid AC or similar OTC acid reducer to at least limit the aggravation of your condition prior to prescription strenght remedies?
If you have a burning pain,where your stomach is located.
Probably.Look upsay MSN Health,and type in ulser see what you can find.