Kitten having hypothermia?

i have a male 4 week old kitten that yesterday and he came close to death.. we took him to the doctor and he put an IV on him to get him warm because he had hypothermia.. and he also gave us a stomach paste that will make him feel better also a can of food with lots of vitamins .. now i try to keep him warm by putting 2 warm water bottles in his cage (one big and one small)..when i put him in the cage and clothe him to keep warm but he get out from the clothes and doesn't want to be near the water bottle .. what should i do to keep him warm?? how can i understand if he is getting cold?? ( when he gets cold his nose turns from pink to pale.. does that mean he is cold??)