I had my gall bladder removed in feb. Of 2002, and have also had the same problems you're having. After I had my gall bladder removed, within a month I had no appetite at all and rarely ate anything.
I was rapidly losing weight and had a general malaise feeling all day, every day. I still had the same symptoms from before my gall bladder was removed as well. The dull, aching, radiating pains and same type of discomfort.
I had the ercp done and they found that there was a lot of bilary sludge in the sphincter of odi, and also that the opening was no longer wide enough to carry the bile through fast enough. They widened that opening and though I can't tell you that the procedure has made all of my symptoms go away...It definitely helped.
To this day, I still have gi problems and have never felt the same from before the gall bladder removal, but the ercp helped enough to get me through some of the hardest parts of it.
You should talk with your doctor about having the ercp. It does have its complications, but it may be well worth it for you.