I'm pretty sure that they do NOT grow their tails back. My vet was talking about this not too long ago, and she thought that *if* they grew them back the tail literally had to be yanked off of the chameleon (say the tail got caught in something out in the wild and the chameleon was forced to flee), but she wasn't even positive about that.
Agreed, chameleons do NOT grow their tails back like Gecko lizards do.
Must admit I do worry you are not caring for your chameleon
I think you should definately get a vet to look your chameleon over. His tail might get infected for example...