Maybe I missed it in the post but do you have low Iron levels? low B12? low Vit D levels? dehydrated? I know its sounds silly but you never know.
I would get a fitbit or some other monitor that can see what your heart rate is while you are sleeping and when you first wake in the morning. Take pulse right when you wake up before you even get out of bed. I had a friend that was way over training and had all kinds of issues due to it. they even had to do the heart restart ( the medical term for it someone might know, AFib???) to get his heart to pump correctly.
Nah, mine does sound different. My stomach is never tore up.It doesn't sound very similar. And there are plenty times when or of know where I can feel my heart rate increase. No matter what time of day or night though, I can always feel my heart beat and always feels like I'm stuck in the flight or fight response. Is your stomach upset a lot of days to? I've noticed that with mine. I can't wait till next month when I get my cortisol checked and the acth test from defy.