I am so sorry you are feeling so badly and that the doctors won't listen to you are help. I have been in similar situations myself and it is so frustrating. I would like to first ask, have you had the Covid Vaccination? The reason I ask is because many folk are having similar issues and it is due to the Pfizer mRNA side effects, unfortunately, it is not publicized so many folks do not know why they are sick and when they tell the doctor, they think they are lying.
If there are any good Naturopaths in your area, I would try to see one of them, they will listen and go into detail as to what they think is wrong and work out a program for you of vitamins, minerals, herbs, diet, etc. When I was living back home in the states, my primary doctor was a Naturopath and she helped me so much, actually more than a GP.
Another thought is to see a chiropractor, now, this may sound odd, but with some cases of dizziness and shallow breathing, you can have some mis-aligned vertebrae in your spine pressing on some nerves that also radiate to the neck, thus causing the symptoms. It certainly wouldn't hurt to try one. He/she will take some x-rays, study them and then go over the results with you and set up a plan, after a few treatments, many folk start to feel better.
I hope that you will be able to get these issues taken care, it is miserable to feel that way and to have no health care professional believe you.
Well, that seems really helpful. If you google does sugar intake cause difficulty breathing, it seems you may have bouts of very high blood sugar, which would cause all your symptoms. Have you done a glucose tolerance test? It sounds like you now have at least something to go on, that may be causing your problems.
Do you crave salt and salty foods, JLuna?
When you say "so much more", what are the other symptoms you're experiencing? Fatigue and dizziness can be so many things - do you have symptoms that are not so common to many disorders?