When would you worry that your slim kid, picky eater, might have GERD or some reflux problem?

Chest pain. The GE junction with the stomach is just below the middle of the breastbone to the left. Affected kids often complain of dull to sharp intermittent chest pain in that area. Symptoms after carbonated beverages, orange or grapefruit juice would also be likely.
GERD. Symptoms of gerd are heartburn, anorexia, regurgitation of gastric contents or vomiting, cough with occ. Wheezes due to aspiration. Peptic stricture causes difficulty in swallowing of solid foods. When these symptoms persist, a GI specialist should be consulted.