Throat inflammation. Be the cause of it?

The patient has Ankylosing spondylitis and GERD. Earlier the patient used to take ppi to curb Gerd but later on he left it and the major issues which he faces is that he has persistent sore throat with thick slimy mucus and urge to clear the throat everytime. And he can't bear eating spicy food he feels like his throat stomach and intestinal mucousal linings are damaged. He has a lax les. Further he also has very poor vital capacity his vital capacity is comparable to that of a chain smoker although he is not he has chest pains as well he feels it's because of Ankylosing spondylitis. His esr and hs crp are always  elevated. He does follow a normal routine and exercises daily. The throat irritation issue are there for more than 1 year. Further he says that whenever he breathes orally then he feels cold in the area just behind the cricoid cartilage just when a person feels when he has sore throat what could be the cause of it? He had a yellow thick sputum discharge recently.