that does look like there may be a bacterial infection there.Ask your Dr to swab and do a culture.
My horrible post nasal drip feels like a block of mucous stuck in my throat. It is always white very thick and sticky and it can wake me if I manage any sleep by choking from it. Nothing has worked. only steam inhalations. The feeling of slime goes down my throat. I so enjoy being part of choirs but with it stuck and on my tonsillar crypts it’s interfering with any singing, as constantly trying to swallow and breathe. Compared to serious lung lobe collapse liver damage and GI extensive inflammation and fatigue this is the worst symptom.