Dust inhalation. Cause pain and cough.

In October I inhaled dust while I was cleaning my guitar since then I feel as if something is pricking in my throat.. I tried a lot of medication even consultations. But yet there is no cure to the pain. I was even prescribed duselpin, even to an extent I did mri and endoscopy but they couldn't find anything. This pain is too much in the morning it's not like any other normal throat pain.. At times the pain radiates below chest and at times hand.. It all started after the inhalation of some small dust probably as small. As a grain of salt.. It's really causing irritation in my throat I feel like coughing all time when I speak and pain too accompanies I need to take steam inhalation all time to keep my throat wet or else the pain is excruciating