I had the same issues with phlegm in my nose and throat. It felt like the phlegm in the throat was ‘stuck’.I would try to cough it up but that didn’t always work. I ended up taking Mucenex and two different nose medicines and that helped tremendously. I drink tons of water as well.
Do you have sleep apnea? I do and I finally went back to using it and my congestion is so much better.
Wishing you luck to resolve this!