The kitten is probably sick, it swallowed a ball and is now vomiting. Even when sick, it plays and is active, but it's vomiting. The mother is healthy and free of diseases. The kitten needs urgent rescue!! By God, I cared for them, but I couldn't take it to the vet. I hope whoever takes it will examine it. Go to the Veterinary Care clinic, their prices are good and the examination doesn't exceed 100.