My 3 year old autistic son has digestion problems. I know this, but his pediatrician just feels his stomach and says he's "fine." When he has a bowel movement, he seems to be in great pain--he arches his back and does a little "dance" on his tiptoes (he moves his legs up and down really fast). When i change the diapers, it doesn't look like his food was ever digested. He eats three times more food than what a "normal" child his age eats, and his stomach gets really hard and he looks like he's 5 months pregnant after eating a meal. He would eat constantly if i let him, yet he barely gains weight (he only weighs 30 pounds, and he used to not even be on the doctor's growth chart, now he's in the 7th percentile). He's on the gf/cf/everything free diet. He just eats fresh vegetables, potatoes, and yams. I don't have him on any supplements at this time. Any advice would be greatly appreciated! Thanks! I live in Pennsylvania, USA.