He doesn't curl his toes in, which is the weird part- he actually has a hard time closing his toes, he's never been able to roost because of it. Otherwise I'd have thought it was mareks a long time ago. I think a sling is still a good start though! And I can still try the vitamins and see if...
We got him back in late winter he was able to walk, albeit somewhat unstable. He had to occassionally use his wings for balance, and we treated him for what we thought was bumble foot, but he never re-stabilized like we thought he would. It seemed like it was something more than bumble foot, but...