I'm not sure I'm clear on this, but you seem to be saying you have an anxiety problem. If you have an anxiety problem, it can cause symptoms because of the stress on the system that you notice even when you might not be feeling anxious. However, they could also indicate something else -- we often attribute everything to anxiety and doctors tend to attribute what they don't understand and don't want to bother with to anxiety as well. But given you've had all these tests and you do have enough of an anxiety problem to have gotten an RX for Lexapro, and enough anxiety not to take it (which I take for prudence, not blind anxiety), let's say it is anxiety. Have you tried therapy? Have you tried relaxation techniques to deal with some of these symptoms, such as yoga, breathing exercises, meditation? Drugs aren't the only place to seek relief.
I have had anxiety for years. Sometimes I get symptoms when I am anxious but there are times I get symptoms when not anxious. I get tense muscles, dizziness, feel off balance, have a heavy head, heart palpitations and body pains. Do some research on anxiety and find what works for you. If you feel you need more help them you should seek some therapy. Best of luck to you.