If. Bm is black does that mean my ulcer is bleeding?

Possibly. Black bowel movements do tend to make us question whether there may be a bleed in your upper gastrointestinal tract. If you have known ulcer(s) that have bled in the past, this could be an indication it's bleeding again and good reason to be seen by your doctor (GI doctor if you have one). .
Hematochezia. It could be bleeding. Usually there is an odor. Iron can make your BM black. If a history of ulcers you should have your doctor check you. Do not take aspirin, Advil or aleve (naproxen) for headache until checked.