A lot of your cardiac symptoms sound an awful lot like adrenal fatigue. It probably would be a good idea to do a 24hr cortisol saliva test to determine the extent of the adrenal fatigue. Once you start supporting the adrenal fatigue, you'll start to feel a little better. The racing heart, etc.. will get better.
canaryclub.org has home kits you can order without a dr's rx. Most doctors, anyway, don't believe adrenal fatigue exists, or they'll order a blood test which only shows your cortisol at the time of blood draw, which is not very helpful. You can normal cortisol part of the day and have low cortisol, high cortisol or a mixture of both, one blood draw won't show you that, a 24hr cortisol saliva test will.