Is she lame? Does she have signs of arthritis on X rays? If the injections have been correctly done (i.e., area cleaned and good injection technique), your horse appears to have adverse reactions to the joint injections. Therefore, you might try to manage her problem in other ways, if possible. Possible options include NSAIDs, Legend, Adequan, oral glucosamines and chondrotin, shoeing changes, and providing her with housing that allows her to move at will (run-in/run-out). Conquer, which is orally administered hyaluronic acid, has been scientifically shown to improve joint conditions in horses. You should consult your veterinarian to see what treatment would be most appropriate for your horse.