Hi. So For Over 2 Years Now I've Been Having

Hi. So for over 2 years now I've been having issues with my throat. It mostly happens at night when I start to doze off. I'll get a sensation in my throat that feels like the tightening feeling right before vomiting, or it feels like I'm not breathing. As an impulse reaction, I'll usually shake my head and wake up. It's only when I'm dozing off, not when I'm laying down or already asleep. Also, some days more than others, I spit up a rubbery mucous. It's usually worse right when I wake up, but some days it goes on throughout the day until my throat's dry and scratchy. I smoke, and I know that probably is the primary cause, but I was just wondering if there are any other possibilities.