I have this as well. The same clear Neverending slimey mucus down the back of my throat it rarely turns into an infection its just there for months. It is worse sometimes than others. I'm having sinus surgery in January to help with it. None of the otcs i have tried really help Sudafed guifenisen nasal sprays. I also have a navage. I feel that it's related to the inflammatory response my body is having to the long covid.