How Can Gastroparesis Be Treated?

My 40 y.o. son has gasteropuresis. I am concerned for him. He is 6 and now weighs 125lb. He daily struggles with being able to keep food or even water down. He was on reglan for awhile and it sez it doesnt work. He says his pancreas isnt working right and now neither is his thyroid. He suffers from hot &cold..breaking intosweats or shivering. Oft times doubles up in pain . I suggested to monitor his blood sugar levels. Eat a diet for gastropuresis. He claims it goes against pancreatic diet and or thyroid diet. His mental health (depression)is rapidly taking hold. It is hard for a mother watch her son suffer so.. Could you help with finding the diet so he can have a manageable life? Im really worried! Can he die from this? What help or hope can you offer Thank you