This may be why when
you eat, the phlegm breaks loose and causes you to cough
, becuz the water you introduce via food
and a drink <span style = 'background-color: #dae8f4'>when</span>
you eat loosens clogged phlegm.
Also, could be you have a sinus infection or your sinuses are stopped up, and it's draining rather too much stuff down your throat, so an ear nose throat ENT doc or even a regular doc, I suppose, can look up in your sinus cavities and see if they can detect a bacterial issue in there, and give you medicine to clear it up.