Hi Suki,
Thanks for rescuing your kit. He probably has worms (mostly all kits have them) and this could be a problem for absorption. If you can get dewormer medicine from a vet that would help.
Do you have access to Goats Milk? In TDKland, we recommend Goats milk.
Cats are lactose intolerant and can’t digest cows milk. Goats’ milk is full of nutrients, probiotics and gentler on their tummies. This can also regulate the poop. You can find it in the dairy section or the concentrate in the baking aisle. Mix the concentrate 1:1 with water or pedylite. If you can’t get Goats milk at the store, you can go to local market or farm. You will need to pasteurize it so follow these steps:
Put milk in a double boiler or in jars in a pasteurizer or canner and heat to 73 celcius for 15 seconds. Cool the milk as quickly as possible, but make sure not to put the hot jars in cold water or they will break. Store the milk in the refrigerator.
If, at any time, he seem lethargic put a dab of Karo syrup or honey in their mouth.
Kittens can’t eat or digest food if he’s cold. So to help him regulate body temperature keeps him warm. I think the best way is to place a heating pad or hot water bottles such as large soda bottles, on LOW, covered by a towel and a soft blanket. Be sure to provide a “cool” spot for him to crawl if he gets too warm. I recommend getting him a soft squishy toy and put it in his nest to give him comfort and extra warmth.
Good luck
PG