help us please

My husband is 71 years old and has COPD and for the past 3 months has been SUFFERING SO BAD with a burning in his throat. Been to doctors, specialists and drugstore. They have tried every kind of drug they can think of but no one seems to know what his problem is coming from. They treated him for GERD, but that didn't work, the latest was this magic mouthwash and that isn't working. When he lays down or reclines his chair the burning stops or when he eats it stops. but the minute he sits up or stands up the burning is unbearable. we even tried a laced no bake cookie and also some wine. NOthing!!! His blood work was good and there is throat looks good. there has got to be someone out there that knows something to help. please