Have you changed your diet? Cutting down on fat intake I mean. This can cause joint stiffness and pains.
I am sure you r have been advised about eating (or taking in supliments) garlic and cod liver oil, but also look to omega 3 fatty acids (also good for weight loss), found in deep sea fish (and also linseed oil, but it tastes aweful).
Also, and this may surprise you, but do you drink a lot of diet drinks? I mean Diet Coke and such. Aspartame has a lot of side effects and it could be worth you researching.
I hope you feel better soon.