Some natural anti-inflammatories may do the trick. One of my big issues with UC was always joint pain. I started taking Turmeric Extract supplements and Fish Oil supplements over the last 3 months and my joint pain has definitely subsided. I would say it has eased the pain 90%. Below are links to the two I use. Quercetin may also be worth a look.
Diagnosed UC 1999
Asacol (no effect)
Colazal (no effect)
VSL#3 (not enough difference to justify the cost)
OTC : Probiotics (Primadophillius Reuteri, 1 capsule per day), enteric coated Fish Oil (1.7g 3x per day), Metamucil (one serving 4x per day), NSI Turmeric/Curcumin95% (1g 2x per day), Caltrate 600D (2x per day), L-Glutamine (9g 2x per day),
Natures Way Alive Multivitamin