Suggest Treatments For Lack Of Peristaltic Moment Causing Vomiting

My nephew who in 2000 was 21 years old. One morning he woke up with a bout of vomiting. He felt better. However after that he started feeling uneasy in the stomach. He feeling early satiety, bloating etc. VEndoscpy test was found negative. All laboratory tests were normal. However barim test showed delayed gastric emptying. He was told that he was suffeirng from lack of perstaltic movement in the stomach, the food was not being digested properly and hence food could not pass to small intestines. He was a hlthy young boy full of energy. It is now 10 years he has been having this problem He has lost a lot weight. We had been to India to consult gastroenterologist who said he had idiopathic gastroparesis or since he voited on getting up, it seems thee was a virus which had infected him. Apparaently the virus has attached his stomch nerves and damaged some of them. Hence lack of peristaltic movement. Can you advice any solution tohis problem. All CT and other tests are normal except for barium meal. His stomach has now sagged. Thank you.