On dosage: all of us here are special cases. I have no idea what anyone will need or tolerate, even on common medications. The only safe thing to do, with any medication, is always to start low and titrate up to a level that provides benefits without noticeable side effects. For the most part starting low means 1/2 a recommended dose, but with several things it has turned out to be 1/4 dose. If it takes longer to get relief from symptoms, that is just the price of caution. A single bad reaction is enough to teach this lesson. Afraid I took longer to catch on.
Incidentally, the SaltStick capsules with caffeine that Gingergrrl warned against are called SaltStick Plus and are sold in bottles with green lids. You can't depend on the color of the bottle itself. I have some regular SaltStick in a brown bottle with a black lid, while those in the advertising show a blue bottle. When I checked that my capsules did not contain caffeine I ran into a problem because the price tag covered the list of ingredients. It pays to check carefully. Most people may tolerate this, but you are clearly not most people.
Just as reassurance, I'm willing to bet you do not meet the clinical definition of Addison's disease. Go ahead with testing, but don't anticipate the worst.