i have small pea-sized yellowish/green, round 'things' in my stool

I have small pea-sized round 'things' that are yellowish/green in my stool. This started a couple of months ago with chronic diarrhea. I have seen dozens. Been biopsied, docs have no idea what they are. Doesn't look like any food i've eaten or a medication. Does this sound familiar at all? anything I should be concerned with? I have been tested already for O&P, specifically Giardia, all negative. Lost 22 lbs unintentionally. Hemoccult tests came back positive. Have had colonoscopy, fluoroscopy, endoscopy, abdomen ultrasound, pelvic ultrasound, small bowel follow-through, bloodwork, lower ct. All negative for anything abdnormal. Abdomen pain, constipation for a week, then normal for a few days, then diarrhea for a week or two. It's a cycle that's been going on for a few months. Almost everything hurts me to eat. Have already called manufacturers of meds I take, no reports of any undigested meds like what i've seen in stool Thank  you!