Looks like kanaplex would be the perfect treatment to try next, sorry, just realised you said a medication. I'd try that now to be honest, you've done a lot of water changing and MB treatment, time to try a med I think. Hope it works and we get a happy update soon!
Also don't be alarmed if you see black edges on his fins as time goes on, that means healing, believe it or not. And the re-growth will be transluscent at first too, then colour up later.
Also don't be alarmed if you see black edges on his fins as time goes on, that means healing, believe it or not. And the re-growth will be transluscent at first too, then colour up later.