Have your doctor test your sodium, potassium, cortisol, renin, aldosterone and ACTH at a minimum.
Addison's is a very serious disorder. If you are craving salt, that may mean your body is not holding on to it. The low blood pressure is also a clue. It can also be an issue with your aldosterone and renin. Adrenals are very complex so you need to see an expert.
Please keep in mind that renin and ACTH are very fussy tests that require a chilled EDTA tube, spun immediately (don't let the tech just put it in a bin) and then frozen as soon as it comes out of the centrifuge. Otherwise they degrades at room temperature. I learned the hard way that lab error got in the way of some of my testing.
Welcome to the Community. As you wait for others to answer you may want to put in some key words from your post into the Community Archives which are located on the right hand side above recent activity. That will bring you to a wealth of information from people like yourself as well as drug and medical info you may be looking for.
Hope this helps,
C~