No medical condition found yet and the doctors so far say I'm healthy and overthinking. My theory is that my central nervous system is weak, but I haven't prove

No medical condition found yet and the doctors so far say I'm healthy and overthinking. My theory is that my central nervous system is weak, but I haven't proven this and I haven't found a doctor who believes me. Could be a medical condition, a diet issue, could be a mind issue - anxiety/depression, or it could be that from training as an endurance athlete, and now that I've stopped running my body is having trouble adapting. I read some research with 4 groups: male endurance trained, female endurance trained, male not trained, female no trained. After tests , male endurance trained had a heart pattern change and the other 3 subjects didn't have the same change. From 14-23 I trained at higher levels for distance running and now I do light walking. I consider myself to be an active thinker, meaning that my mind is always contemplating some topic. Does my brain burn more calories than Expected and does it need certain nutrition to maintain health? The diZiness is a miscommunication between the heart and the brain. I don't know..I've had dark chocolate and granola trail mix near me between meals the last 2 days and I've had no dizziness.