Sounds like it has a respiratory problem. Antibiotics may help, vet visit ASAP. And do make sure you are feeding it in the correct position - on it's tummy head up, as when feeding from mum, and not too fast.
I agree, be very sure that the kitten is in a laying down position otherwise the milk can move into their respiratory system. The vet can give you some antibiotics to help. I also found that putting the babies in a washcloth so they can not wiggle too much helped but I kept their paws out because they will still pat you hand as you are feeding them. Similar to what they do to the mom.