Another update: x-rays show a lot of abnormalities as suspected. Vets are concerned he may be in chronic pain. We are trying pain meds to see if his behavior changes. Another x-ray in 3 weeks to see if the spaces in his joints are decreasing. The difference between his xray and a normal squirrel's his age was clear. He had large gaps between the bones at the joints and the bones in his front legs are much shorter than normal.
He is up to 205 and chunky. I think he is doing great. The improvement from a couple weeks ago is huge. He is going in a litter box and started to run a bit. He is super clumsy and his back legs clearly don't work right. He hops a lot. He just started play wrestling with his stuffed toys. He is loving the mixture of baby food, formula, yogurt and crushed zupreem primate biscuits. Top front teeth have started to come in but seem slow and stunted. Bottom teeth were very long and the vet trimmed them. Not eating solids well but loves to chew on the inside of an acorn or nut. Some he swallows and some comes back out. I have to hold the nut while he eats as he doesn't grip well and would fall over. Tried a cuddle-bone and he LOVED chewing on it.
When he climbs I always have my hands under him as sometimes he just lets go. He goes up but can't come down. He is so goofy. Just love him! Thank you all for such good suggestions. I would have been lost without your help.