Thank you for writing here. I understand how traumatic the experience in your childhood might have been for you. Having fear of blood is common among the general population.
Worrying about your health is good, but too much of anything is bad, so maybe it would be beneficial for you if you could go in for a complete health check-up to rule out possibilities for any ailments you might think you have. This should help in putting your fears, doubts, and anxiety to rest.
A root canal is a fairly painless procedure and the dentist aways numbs the area before starting with the procedure. It might be the pain which is causing you to feel so.
I suggest you take up meditation and other relaxing activities and new hobbies to engage your mind and prevent it from overthinking so much. Go for a walk, exercise, and engage in physical activities. It will help consume the extra energy the body produces.
You can always have a one-on-one chat with the experts on this platform.