I quit taking 1/3 of daily ultram meds & started getting black tar like stool along w abdominal pain. are the 2 events related or maybe a coincidence?

Coincidence: Probably a coincidence but you should see your doctor be checked to make sure you don't have bleeiding of your gastrointestinal tract.

See doctor soon: Black tar like stools are indicative of bleeding in the upper gastrointestinal tract, usually. Decreasing or even stopping a medication like ultram should not cause or worsen such a medical problem. You must go to your family doc or GI doc soon to have this checked out.

Constipation: Ultram and its class may cause constipation which can possibly lead to black tar like stools (blood in stool) with abdominal pain. A colonoscopy and upper endoscopy would be wise. Switching to a different type of medication for pain control may help.