I don't know if this is a way to keep him going.
I'd try 1/2 or 1/4 of an earth worm, or a whole red one.
Maybe a honey bath, 1drop per ounce of water mixed with clear pedialite 1/10 water. I've heard this helps their energy level and increases appitite. I think if had works he would eat and not gain weight. They wouldve errupted through his skin by now. I don't know. Maybe the baths and a visit to the vet.

I think baby food has allot of cereal, he would need protien. Force feed crickets or worms