Like Lifts said, take Knox Nutra joint which is basically gelatin and the medical community has known for years that powdered animal cartiledge helps heal knees and other joints.
Fish oil is expensive, but it is certainly the gold standard reducing joint inflammation by brute force of its EPA, and the only reason I don't use it on as regular basis is the cost factor. Your body can only convert a small amount of omega 6 from flax oil to the beneficial omega 3. Fish oil is omega 3 to begin with. One of the most reasonably priced brands is Spring Valley enteric coated from walmart, no aftertaste.
If you can afford it, take a tablespoon of fish oil twice a day until the joint pain subsides. The capsules are okay for maintenance, but not potent enough to reduce joint inflammation. Use the Knox gelatin and vitamin C like Lifts said. If you can't afford the fish oil, flax works nearly as well and tastes better, but you need 4-5 tbsp for joint relief.
The court of last resort is Adequan, developed to repair joint cartilage in horses. Only available for VET use and hard to find, but it's worth the search. I have a female friend 28 yrs old vet tech who had 2 torn rotator cuffs and was ready for surgery until the vet gave her a shot in each shoulder. She told me she felt like superwoman for nearly 6 months and although some of the pain returned, it has never again been bad enough to consider surgery.
My 14 year old dog was in so much pain with arthritis this time in Sept '07, that she wouldn't eat, was puking and I had to carry her outside to potty. My vet said it was a pain incident and he could feel where a disk used to exist at the L-6 location. 24 hrs after a shot of Adequan, I had to keep her from jumping up and down off the couch. 12 months later, she was still running and jumping nearly as well as when she was a puppy.