To begin with, one month is way too young to be away from his mother -- kittens are not weaned until around 8 weeks of age, and 12 weeks is the youngest a kitten should be adopted out. Where did you adopt him from? He isn't eating solid food, at four weeks of age? Of course, as with human children, ANY medical problem should be referred to a doctor (veterinarian) at once. Do not wait! Kittens, especially, can go downhill very fast. GET HIM TO A VET AT ONCE. Thank you...I pray he will be all right.