I would say yes it's from anxiety. I've had diagnosed anxiety for 10 years but really I've had it as long as I can remember. When I was a teenager I was always afraid of having a heart attack for no particular reason. Every time I would go in a movie theatre I would get really anxious and have a racing heart. And I'd never eat popcorn because I was afraid I'd choke and die. Lol seriously anxiety is awful. The physical symptoms and mental stoms are hard to deal with and to overcome.
And for whatever reason now I always get lightheaded and hot and sweat when i go in a Walmart.
I feel your pain its just pretty crazy how your mind can create all of these things! Lol
All of this is anxiety .... If you keep thinking about it the worse it will get .. Try to relax accept they your heart is healthy and live your life ..