Hi welcome. May I ask what tests he had on his limb? I mean mri,bone scan etc?I ask because of why he is in the air cast? Of course you need to follow the doc but I had a big mistake made with myself and being in an air boot. My issue is in my inner ankle/foot/calf. I am sorry I don't have advice on the treatment other then maybe he needs a different pain doc. Is this pain doc very familiar with rsd? If not I would try to find one who deals with this. I really feel that is key. I have seen 4 pain docs and gotten 3 different things they wanted to do for pain relief. What I have realized is you can't always go with the first thing suggested. I know how bad it is to want relief but I also feel one has to research a little which when this first happened I didn't. It has been about a year and half for me. Seems like million years so there are others here that are more knowledgable. Hang in there and he is lucky to have you