Hello, my name isXXXXX and I have over 20 years of experience as a veterinarian.
I understand that you are concerned about Shy's potbellied appearance.
In most cases kittens with a pot belly have a large number of gastrointestinal parasites. Once we discover what parasites he has and treat them appropriately his abdomen should look normal.
Rarely an enlarged abdomen can be a sign of something more serious, especially if it is fluid filled. It can be a sign of a disease called FIP (feline infectious peritonitis), heart disease or a congenital organ defect, such as abnormal liver vessel formation called a portosystemic shunt.
If he is bright, alert, happy and playful, eating, drinking and growing well then I highly recommend having a stool sample checked by a veterinarian and treating him for common parasites with a wormer called pyrantel or Drontal (pyrantel and praziquantal) which is even more comprehensive.
If he seems small for his age, not eating well, and isn't active and alert, or if his abdomen has fluid in it then we should look a little closer for a cause and be more concerned.
Please let me know if you have any further questions.