Is the black kitten nursing mama? You need to make sure this kitten is nursing and gaining weight. Kittens cry when they are hungry. Please determine if this kitten is getting sufficient food. If not you will need to hand feed. If they do not take the bottle you will need a syringe or dropper. Two drops in the side of the mouth at a time. On their tummy, head slightly up. Let them swallow and give more. About 2 to 3 ml per feeding per kitten. They need to be pottied after eating, which is where you take a cotton ball and gently rub or tap their bottom until they go pee or poop. This must be done unless mama will do it. Please use KMR to feed. Let us know how it goes, but the black kitten is probably hungry and will not survive if you do not feed it.