My Nutmeg was diagnosed (by her vet of 9 yrs.) with Addison's and started the mess and shots. Then - long story, found out she didn't have it. Guess it can be very hard to diagnose. Maybe you need to see a specialist? We did, thank goodness! Also there is a great Addison's Yahoo group with a wealth of info.:
https://groups.yahoo.com/neo/groups/AddisonDogs_/info
I know how frustrating it can be. Hang in there, you'll find the right answers!