GM
I found it helpful to rinse my mouth occasionally with a cup of warm water and about half a teaspoon of 50/50 salt and baking soda.

But, I didn't have bad mucous or mouth sores, so I am not sure if this would help under those circumstances.

If John can; try sipping heavy juices like grape(try red, white & purple), blackberry, & pomegranate. I found they seemed to help control the bad taste, but even these would taste OK one day, but not the next so I rotated them.