Some CD and UC symptoms can be brought on by a fungal condition...overgrowth of fungus/yeast... maybe triggered by antibiotics (even decades ago), birth control pills, moldy env't, etc. The only way to know is to experiment a little. Eliminate grains, yeast, sugar (an antifungal diet) for a week or 2, and see if you feel better. These foods feed the fungus and make the overgrowth problem worse. I didn't realize my 8 years of UC suffering were a result of a fungal condition, until I went on an antifungal diet (even when my doctors told me there was no link) and within 2 weeks, my symptoms virtually disappeared. I too had D, mucous, gas, pain, blood. I still try to stay on a somewhat modified diet. I "try" to stay away from yeast and too much sugar and grains to stay well, but still enjoy a brownie or two when I want :) BTW, RA has also been known to have a fungal etiology. As for the scope...love it. The prep is awful!!!, but the actual drugs they give you to knock you out are sweet :) That's just my opinion, of course. I'd have the scope, if I were you, just to find out for sure what's going on in your colon. Can't be too careful.
You may want to consider the elimination diet, just to rule out fungus. It is a real issue that is overlooked by most doctors. You may be pleasantly surprised, like I was. If you want more info, you can email me directly. Nothing special about it, just eating meats/poultry/fish, as well as veggies and limited fruits...as much as you want. Real food. Take care.