Why won't my child eat/gain weight?

My son has never really had an appetite... He just turned 2 two weeks ago and he weighs 19 lbs. He's weighed 19 lbs since August 2008. He's gotten taller (he's currently 32.25 inches); however he's really, really skinny. I can't get him to eat anything other than rice, pasta, fresh fruit and a fresh vegetables (sometimes he'll eat string cheese, pizza, or katsu chicken). He only drinks water and breastmilk. I've tried Pediasure, but he won't drink it. I'm so frustrated and worried about his weight. I can't seem to find a half way decent pediatrician for him who cares that he hasn't gained weight in 15 months. How do I rule out an underlying medical issue without the help of doctor who seems to care?

[Renee Radenberg]

His weight is below the 3rd percentile and his height is just above the 10th percentile for his age. It is frustrating when your child will only eat a small range of food. From what you wrote he does not eat that much protein source foods and he is a 'picky eater'. Suggest using cheese and meat sauce on his pasta and rice, yogurt on the fruit, and cheese sauce on vegetables if he will accept it. Suggest making breast milk shakes with breast-milk (pump it) and ice cream blended and see if he will accept it. Give him them at every meal for additional calories and protein. Try to make regular milkshakes with chocolate milk and ice cream blended. Sometimes 'picky eaters' will accept these milkshakes when they do not like pediasure, plus it may be easier on you without using the breast milk. The most important aspect is to relax at meals and not to force him to eat. Let him eat what he wants no matter how limited. Suggest a daily chewable children's multi-vitamin if his eating pattern continues. Slowly introduce new foods, and if he does not want it, do not make a fuss over it. Let it go and try in a few weeks. Hoped this helped you.