My daughter had the same problem. Notice I said had. She is taking a Weight Gainer product and it is helping. Also Purple Cone Flower Root (Root of the Echinacea flower) gives you a voracious appetite. My daughter has gained 10 pounds in about a year.... but, hey, it's an improvement. She has trouble eating food and sometimes just can't stomach thinking about swallowing it. She says her main problem is a gag reflex that is too sensitive. She is still skinny, but looks better than she did. - She says she has to concentrate on chewing and swallowing in order to eat because if the food gets to the back of the throat before she's ready, she has to spit it out...
Hope this info is helpful. Wishing you the best.
take her to a upper GI doctor have the same problems. good luck.