I do not know in your case, but I had a lung fluke (definitely) and did not know it until I started taking prazi for something else, which seemed to alarm the lung fluke (or something) into making its presence none.

These were my symptoms -- all of a sudden one day I belched and my mouth filled with the horrible taste I have come to associate with the odd tinge to the odor of my stools since I have been passing parasites, mostly flukes but some worms. (Besides the plain old smell of feces, there is a sort of fishy overlay; smells a bit like a dead frog in formaldehyde I dissected in eighth grade. Yuck.) Anyway, after this ominous warning, I developed this hellacious tickling in the back of my throat, like I had to hock up some mucus that I could quite hock. I kept trying, so I spat and spat and spat.

The sputum was very distinctive -- sort of bubbly, thicker than normal spit, and very light tan (I later learned this was dilute blood, but it was too pale for me to guess it was blood).

I filled like half a paper cup before it subsided. I also noticed the odd tiny brown dot in the sputum. This went on off and on for a couple of days before it stopped for good.
I imagine because the fluke(s) died. (I had kept taking the prazi. I also started a course of triclabenzadole soon after, so I can't be sure which got them; probably both.)

I have found one lung fluke in my stool but I haven't been digging it through it as assiduously as in early days so I may have missed more. The lung fluke I thought was a drop of blood, except it didn't dissipate into the water.

Here is a picture of a paper towel I was spitting into -- the three brown blobs at the top were originally greenish when they came up, and I only spat three up total, all at once near the end of this particular ordeal. I later id'd them as p. westermani ova. But they took a mighty hock to get. The brownish stuff elsewhere is more typical. Note the brown fleck near the bottom.

This may be totally irrelevant to your case, but I did have the sensation of stuff in my mouth, definitely.