What Causes Difficulty In Eating And Drinking And Vomiting Afterwards?

My dad may suffering from Hyperactive thyroid, but not sure if thats really the case. But from what I have gathered. He cant keep any liquid or food down, as soon as he drinks or eat something he throws up. He was admitted to the hospital but Drs in the Philippines are useless, after several lab test, 2 xrays and an ultrasound, they cant really pinpoint the problem, other than his " kidney stone" came back. Which btw, is totally unrelated as to why my father complains of difficulty to eat and drink without vomiting all of it. And his sense of smell is apparently very active and very sensitive, and he throws up from pretty much anything he can smell .. food and moms cooking. So, the sum up the problem. He has stomach pain (from starvation i guess) each time he drinks and eats and the end result he vomits. he is very weak, he just lay around and he is soo skinny. My mom is giving him Ensure and milk, so at least he has some nutrients in his system. Any insights, will be greatly appreciated. Thank you so much.