How to know when post nasal drip is sinus infection? sick oct 19-28. post nasal drip started oct 26. sometimes yellow sometimes white. using flonase and saline. clearing throat often and funky voice. some nasal congestion no runny nose. no other sx?

Post nasal drip: Usually with post nasal drip it is thin and clear , can have the clearing of throat and change in voice. Typically with sinus infection the discharge is thick and yellowish/greenish in color. Also you may feel pain around the nose and forehead area. Can also have a mild fever with sinus infection. Sounds more like post nasal drip in your case.