I know 'exactly' what you are saying and what you are going thru! Except you seem to have them more often and more frequent.
I get that feeling tho shortly after lying down. It is definitely scary because I feel like I am seriously going to faint. My heart palpitates terribly and I get what I call 'inside tremors'. It is like shivering, except it's on the inside. I would always tell my husband what is going on just in case.
When it first began, I surely wondered if I will still wake up in the morning.
I noticed that if I sat up in bed, they subsided rather quickly. So I began building my (3) pillows up and it has helped somewhat. I never got too many per night. Mostly just when I first laid down. Sometimes just as I fell asleep. I would jerk awake like I was shocked I guess. Actually it was more like a "forgot to breathe" feeling. I figured they were like a herx-that is what most people told me.
They have been tapering off now so am not having many at all now.
Try sitting upright and breathing calm when it happens or try keeping head propped up higher. Maybe that will work for you.
I hope those feelings soon subside for you as I know they are very uncomfortable