If he's chomping carrots his teeth are probably doing well enough not to bother him to this extent. Have you thought about parasites? I have no experience with meningeal worm, but I know it lives in wet areas and affects the spinal cord. Did your vet run a fecal to check for parasites before worming him? Not all wormers are created equal and they don't all target the same parasites. I'm glad to hear he's eating something. Bananas, carrots, tomatoes, bread, etc. are all better than nothing. There are times when it's important to feed them what they want to eat instead of trying to force them to eat what we think they should eat. Will he eat fresh leaves?