How Can I Break Down Thick Phlegm Stuck In My Nasal Passage That Is Causing Pain When Swallowing?

Hello, I have been to the hospital twice now. Once last night(May11) and again this morning(May12). I am sick with something like a cold or the flu, I passed the covid test. I went in this morning because I believe I have a large piece of phlegm stuck possibly in my nasal passage and it hurts when I swallow and is irritating when I don t. It has been almost 24 hours with it. (7amMay12-Now) They looked with a flashlight down my throat the normal way and then did a cat scan. My issue is I don t think a cat scan would even show it. They said it looks like swelling from being sick but I know by feel and memory what phlegm feels like so now I seem to just be stuck with it and am having trouble sleeping. Any advice to break down or dislodge it?