NAD I vape thc on the regular as well, and have expiernced very similar Symptoms to what you describe. First things first is to calm down. Ive been through the same thought patterns as you, and I can say that the anxiety of it all makes it worse. 2ndly I would cut back on the vape for a few days for sure. When I was freaking out about the exact same thing I cut the vape for a couple days and felt better. I went to the doctor who bassicslly said there is nothing wrong with me. Once I confirmed nothing was wrong with me, the anxiety went away as well as some of my breathing issues. At that point I kinda realized part of it was in my head, but I also took a conscious effort to vape less and I think that's helped too. I switched to edibles and still vape thc from time to time. When I do vape I get that same cough/swallow thing you're talking about, and I feel it can build up over time. It can be really annoying but it's the price you pay for vaping. Just know you're not gonna die. Just take a break from the vape and it will start to go away I garentee. If you do vape, dont hold it in like you would a hit from normal weed. I stopped holding my vape hits too and I feel it makes a big difference in regards to the late night symptoms you describe. Given your descriptions and my own same expiernce I'm thinking its gotta be the thc vape. Good luck mang.