Shelly,
I am sorry you are having to go through this. Going through diagnosis, and then proper medication management is tough.
I wholeheartedly agree with everything that Wanda, Terca, said.
The medical community really needs to have raised awareness of addisons. It HAPPENS!!! They need to know about it and make the diagnosis. Unfortuately all to common that it is a delay in diagnosis.
If you are on 20 mg of prednisone a day, you are over dosed. I personally had bad side effects from prednisone (made my headaches worse, seemed to poweful, gave me skin sensitivity) I far prefer the hydrocortisone. I have less side effects, and it has been easier for me to figure out how much I need. The down side of hydrocortisone is that you have to take it more often daily. I find that it starts to wear off in about 4 (to tops 6) hours after I take it. So I will take it 4 x daily. Largest dose in am with 2 to 3 doses after that. Below is a wikipedia reference about glucocorticoids, discussing relative potency, so prednisone is 3.5 to 4 x more potenet than hydrocortisone. Too much glucocorticoid, and you will have side effects from the medicine, too little and you will get the addison's sypmtoms.
http://en.wikipedia.org/wiki/GlucocorticoidAre you on florinef? Have they checked your aldosterone? Or is that what they are trying to find out now?
I also agree with the girls that your thyroid should be even if TSH is as high as 3 to 4. I think many on this site will tell you that they feel best if the thyroid is directly in the midrange of normal (1 to 2.5 for TSH). This also assumes that your pituitary is working, so they need to check the T4 level as well (and that should be in midrange of normal. )
I had horrible headaches, (head pressure really), difficulty moving my eyes, and felt like I had dropped about 20 to 40 IQ points. The florinef and hydrocortisone made it better, but I did not truly start to have days without head pressure until both the glucocorticoids and thyroid were adequately replaced.
You will be rapidly becoming an expert in this condition, and know your own body. No matter how well intentioned a doctor may be, they will not know exactly how you feel, because text book reading is only an approximation. Many gals on this web site have seen Dr. Friedman in LA. On his website, goodhormonehealth.com, under "contact us" 3/4 way down the page, there is a "Physicians List" which has a list of many docs around the country who have traine d with him.
There is another web site, which I had run into years ago....which back then I thought was a little weird.....and now...I am amazed at how accurate I think it is about a lot of things. (NOt that I believe every word.) "stop thyroid madness", has been interesting for me to reference. There is information on that site about adrenal gland disorders, and it talks a lot about the interplay between the adrenals and the thyroid.
If your back and leg pain does not go away with proper medication treatment, then it needs to be worked up further. It could be a consideration to do just a plain x-ray (or later MRI) to make sure you do not have a bony abnormality or disc issue.
Hope you are feeling better and better.
Shannon