Possible a good idea to get a 24 hour EKG reading, ask your doctor. I suspect this is inappropriate sinus tachycardia or another ANS malfunction that can have a physical or a mental cause.
My suspicions are, of course, worthless, but it's really clear you shouldn't feel dizzy and get a heart rate of 200 upon light excertion.
See your doctor as soon as you can, there's no need to suffer from this unnecessary. It's important to determine if your rhythm is normal when your heart rate is 200, and what your average heart rate is I think. Your doctor will give you more specific answers
My first thought is to see a doctor about this and take all your readings with you. You could have weak adrenal glands, they can cause the low blood pressue but usually not the high heart rate. It could also be thyroid, but, that can cause slow heart and high blood pressure, so, I doubt if it these two problems.
Normally, I would say this was a sign of shock, but, you have been having this for so long, I doubt if that is the case with you.
I would not be too concerned, but again, as I said, I really feel that a visit to a doctor is in order; he/she will know what tests to give.
Hope you feel better and keep us posted.