To simply answer your first question: YES, it is not only common, but expected, to have autonomic symptoms that come & go. Most of us with dysautonomia have waves of symptoms that last days/weeks or months. It's best to be tested during this time.

As for the OH and errors on readings while moving. It should still be accurate if you stop moving as soon as the cuff finishes inflating. If your problem is just when moving, then request a treadmill stress test. They take BP's and heart rates while you are walking...yet your arm is stationary/still on the bar in front of you so no errors will occur. You can also try BP's at home doing things you know makes it drop and just hold your arm still or be still once it inflates. Make a journal of activity that causes symptoms and record readings that correlate to it. Then repeat these in the doctors office.

I don't think AAG antibodies vary...they are either there or they are not...as in most other autoimmune diseases (whether in a flare or not). So I don't think your would have to be in an active state for them to show up. BTW, did you have a workup for autoimmune conditions?

I understand your frustration with one-size fits all for testing...particularly with a condition that symptoms wax & wane. But it appears they responded (not discounted) to your reported symptoms of IST and treated with what is usually a first line treatment...beta blocker. It's unfortunate that your had a negative reaction. Are you still having problems with the tachy rates? Is 110 the highest? Have they tried other medications?

Sorry I can't be of more help. Your BP is unusual and the fact that it returns to normal when standing still (vs drops) is sort of outside the box for OH. However labile BP can be problematic also. You will just have to practice various techniques to record BP's in different situations/activities. Most home BP monitors save the history for some time period. When you've collected numerous readings that show your problem, then take the machine with you and scan through the history to show the doctor the actual readings. Maybe this alone will help avoid further (hit or miss) testing. A good autonomic specialist KNOWS that symptoms come & go and should take this into account when testing and setting up testing during those time periods.