I remember one time when I could tell that Melanie wasn't feeling "sick", but she definitely seemed stoned - in a pleasantly loopy sort of way. The vet assured me that I shouldn't feel bad or guilty that I was being a "drug pusher". We agreed that she "earned" the right to remain loopy if she wanted to, and it wasn't such a bad way to be given the alternatives!
Vincristine and Elspar are good, effective drugs. Please just remember to take one day at a time, and cherish each one. Smokey doesn't want you to be stressed and worried. He is with you now - these days are part of his life just like any other. As difficult as they are when you are so concerned, he is spared all that fear - and is just living each day as it comes.
I know how hard this is, and I really feel for you. I don't want you to have false hopes that he will come through this and be five years old again. I wish I could wave a magic wand and make it so.