My cat recently gave birth to three kittens and it has been two weeks .one of them has recently gotten very weak he seemed normal a few days ago and was growing but since yesterday he is very weak and is not feeding I have tried placing him directly on the cat's nipple so he could feed but he won't take it I tried giving him milk through a dropper and he won't feed on that as well. He is so weak that he just stays in the same position. I don't know what to do