Oh that is good news, the sleep will have done him good, eating and drinking is good too, has he had a pee or poo yet?
Poor soul he must be so confused and poor you as well, it's just so upsetting when they get themselves in a state and you can't console them or explain things to them....
It really sounds as though you are doing the absolute best that you can and giving him the best chance to get through this, the rest is beyond our control sadly.
Still sending good thoughts for you all.