I think this could be MBD. You've said earlier he seems lethargic/having troubles moving, no calcium supplements (don't blame yourself, I can see where you were coming from w the butterworms), not eating, and the back legs from that last pic seem a bit off to me.
I want someone like griff to chime on though and give his two cents, but I would say this is MBD.
What are your enclosure conditions? How big is the tank, day/night temps/humidity, what kind of substrate and how deep is it, are you treating his water with reptisafe or something similar?