I had gastric bypass in Feb of 2003 and I have lost and kept off 210 lbs (I was 325 now I am 115). The weight loss has helped some, but I still live with pain.
One thing to remember is that with this surgery you can never take any NSAIDS ever again, and that is really huge. I can take Tylenol or narcotics and that is it. That has probably been the most difficult for me. But I survive and I am much healthier than I was.
I have short gut syndrome, and I do not absorb medication very well, so I have to take meds in other forms, I am on Fentanyl patches, and I take Oxyfast (liquid drops) for breakthrough pain, and for migraines I have Imitrex shots. It took several years for them to figure this out, I would be on an antibiotic and get sicker to the point that I would end up in the hospital needing IV antibiotics. This is a great article about that http://www.ajhp.org/cgi/content/full/63/19/1852#SEC5 I have printed it and taken it to all of my doctors, they are finally listening to me.
This does not happen to everyone that has this surgery, but you need to be aware that it can happen.