Can't find the bleeding - looking for suggestions

Hi, My 80 yo dad has had ulcerative colitis for 50+ years and has controlled it pretty well except for the occasional flare that requires steroids. In fact, it seems that the older he's gotten, the better his UC has been. Anyway, I'm not sure if this is something that really belongs in the UC forum, but we are stumped, the Dr's are stumped and I'm just looking for suggestions. For the past 3 years, every 8 months or so he has an issue with what we assume is upper GI bleeding. He gets run down, has black stool and the next thing you know he's getting a blood transfusion because he's so low on blood. Last June, he was in the hospital for a week because he collapsed at the bank. Upon arriving at the hospital by ambulance he vomited tons of blood. At that time his HG was down to 5. In the past 3 yrs he has had 4 colonoscopies, 3 endoscopies and swallowed 2 cameras and they never find any signs of anything that could possibly be bleeding so much. It's like something opens up, bleeds like crazy and then shuts itself off without a trace. Any suggestions? He was admitted again yesterday for the same issue. Sunday his HG was 9.5 and by yesterday it was down to 7.5. He's going to have another colonoscopy tomorrow and if they find nothing and his blood count stays up they are just going to release him with no answers again. Frustrating! Don't know if it makes a difference but he's in really great shape, not at all an "old" guy. One last thing. He's never had a ton of visible blood when having an UC flare. Unlike me, who is a bleeder, he's always been mostly mucous and diarrhea when he's in a flare.

My FIL was having a lot of issues with black stool and vomiting blood. He had 10 ulcers, 5 in his stomach and 5 in the duodenum. His were clearly visible on the endoscopy, however. He was diagnosed with h. pylori.