When my DD was little she had really bad reflux and wouldnt eat anything, and couldnt sustain body weight. She went to the gastroenterologist and he did the scope for Celiac, food allergies and everything. SHe was 1. She had this done 3 more times by the age of 4. She did have welts lining her espophagus, stomach and intestines, but all the tests kept coming back normal. She didnt eat daily, sometimes not for two days. She did drink lots of milk. When she was 5, we went to the allergist and had the skin prick for a huge variety of foods. Nothing....
Finally her pediatrician decided to do the blood test for shellfish, dairy, egg, whole egg, stuff like that. Turns out she was highly allergic to dairy and egg. Her reactions were totally internal, so we couldnt tell. she just would stop eating, and since she had done that from birth, we didnt know what was wrong.
When she was diagnosed with the food allergies she was 5 1/2 and only weighed 28 pounds. We did a strict diet, with no dairy, or dairy proteins, (casein, whey) no egg. She did great! She outgrew it 2 1/2 years later, and it was the happiest day of her life. She is going to be 9 and is 65 pounds!!!