Been heading out the door past couple hours so I am distracted and thinking in pieces, sorry for so many extra posts to you.

I assume your other 2 cats have all their shots current and that you are keeping this baby seperated from them and disinfecting hands and dishes etc between him and them...

If not, please start. :-S

it is possible that the wormer has made him nauseated and caused the diarrhea. It's possible he has some disease as well. It's possible that the cow's milk caused the diarrhea. But the main thing right now, given his young age, is to keep him hydrated and warm and calm and feeling safe -- oh, and segregated from your other cats. And you should wash your hands between handling him and them. I've had to deal with this and though it looked like I'd never succeed, hello! that little runty sick kitten is now almost 13. Now in mine, his digestive system was ruined because some kids fed the litter canned cat food at only a couple days of age. He still has IBD from that. What saved him was syringe feeding with a formula my old country vet recommended: of milk (yes, regular milk), egg yolk, a bit of corn syrup, a squeeze of Felovite cat vitamins, and most importantly, some gelatin powder mixed up in it. It was the gelatin that seemed to do the trick and I've used this umpteen times in other cases since then. I'm sorry I don't recall the exact amounts off the top of my head. The canned food is too rich in this situation, too hard to digest. Most small kittens should be able to handle cow's milk. If he's this skinny and is only one kitten (he should be big and fat), the other kittens have died (why, we don't know) and he's been sick awhile. Good luck with this one, I'll be thinking of you guys, but gone from computer as of now till Monday.