It probably hurts too much to move around, but swimming is easier than walking.
He needs an x-ray to find any spinal problems, and a blood test to check his metabolism.
In the meantime don't let him climb sofas or chairs, and remove climbing objects within his habitat. That way he can't injure himself more.
I watched a grown, seriously MBD rescue iguana climb down from my sofa, and she landed on her chest, with her rear bending sharply over her head. She was totally paralyzed after that. I had no idea that a 14 inch slide to the floor could result in that.