Is there a ring of what might be layers of multiple stuck shed on his tail? This can happen if they are poorly housed with low humidity and not fed properly. it will eventually cut off circulation and cause tail rot.

If there is no ring of anything that might be hard, built up shed, then for some reason, the tail area may have scale rot.

Why it would only be the tail is a mystery but if it is not improving on a daily basis, it really does need an exotics vet.

The mood change is probably hunger. He went a long time without food. You finally gave him what he considers food and you kick-started his feeding response. That coupled with the discomfort he must surely be in if his tail is that far advanced. As was stated already, don't be concerned about him striking at you, be concerned about his health and tail.