I have two four and a half month old kittens. one has had runny pooh that we just solved and gained half a pound in like a week. the other hasn't gained any weight in a couple weeks now. he seems to be eating. super hyperactive. he looks bigger than his sister. but he weighs 5 pounds and she weighs 5.5 pounds. is it normal for kittens to plateau for a couple weeks here and there if everything else seems normal. he eats. he drinks. his pooh looks normal he plays hard. sleeps hard..