Why do I keep waking up feeling like there's a fleck of spit caught in my throat?

[Irwinad]

I've had this problem for a little while now, but it's been getting worse. During the night, I sometimes wake up with the sensation of have a fleck of spit caught in the back of my throat. Like I've accidentally inhaled a bit of saliva. I've tried looking up people having similar problems, and a lot of people mention mucus or phlegm or catarrh, but I distinctly mean spit. It's like when you accidentally inhale a bit of water. It doesn't feel thick or sticky or like something is coating my throat like post nasal drip. It cause me to desperately try and clear my throat. I cough shallowly in an effort to try and keep the spit from being inhaled, but nothing comes up. Sometimes when the sensation wakes me up, the cough is so strong and so shallow it causes me to gag, and on several occasions it's caused me to vomit. I'm desperate to find a solution. The fear this causes feels sort of like drowning. Almost like I wake up just in time to try and stop myself from inhaling saliva, but there's nothing I can do to make the sensation go away. Any help is greatly appreciated.