Whatever you do.....DON"T drain it......once you start that, you have to keep it up and it gradually gets worse and generally solves NOTHING. If your cool room is big enough....let him run loose....even if it's a little close quarters. That'll do him more good than anything. You can pulverize the motrin or ibuprofen and top dress his feed with it and that WILL help, and just be careful when clipping the leg out to try and disguise the swelling with hair around it.