My husband initially took Prednisone after getting strange lesion...

My husband initially took Prednisone after getting strange lesions, severe joint pain, severe fatigue and severe stomach cramps/nausea. It worked great he was tapered off and no problems for about 18 months. Then he go sick again (2/08) and has been up and down on Prednisone for 7 months- currently taking 60 mg. daily. Some doctors think he has Wegener's, but testing is inconclusive (Wegener's starts with upper respiratory stuff, which he also had). His mood swings are severe and he's a different person, twitching, hand trembling, muscle spams, malaise, anxiety/depression, very fatigued, insomnia, severe stomach cramps/vomiting. How do you tell which symptoms are the Prednisone and which are the disease process? They want to taper him to make him sick enough to get some test results that show organ damage or something, but everyone chickens out and he ends up getting increased. How long should he be on Prednisone and not be put on something stronger?