Ahn, here is a tip that helped me enormously when I was just about choking on that gunk. I rolled up clean gauze and put it in the lower sides of my mouth, between the teeth and the cheek. This absorbed a lot of it and allowed me to sleep, propped up of course, for several hours at a time. It also helped when I went out in public. Make a roll about the size of your index finger, one for each side and see if that helps.