Need Help

I just got a new 12 week old male kitten from a place that saves animals that are going to be put down, the lady takes the kittens in gets them checked out by a vet, and if they are old enough she will deworm them and give them advantage like she did ours. She gives the kittens away for free, but I am worried about how small our kitten is because I have a 14 week old female and she is much bigger. My female is very active, but the new male only wants to sleep.....do you think he is ill or just scared about being in a new place?

Hi, your other thread about this kitten has received several replies. See here.