"Extreme fatigue" is one of the primary symptoms of adrenal insufficiency. Autoimmune disorders like PMR also cause fatigue but not the magnitude of fatigue that people experience when their cortisol level is too low.

Approximately 7 mg of prednisone is when people begin to experience a shortage of circulating cortisol in the body. Somehow you need to find a way to maintain the 7 mg dose of prednisone and continue to decrease your dose over a long period of time. It is why we are instructed to taper off prednisone slowly in the first place.

I completely understand why you would increase your prednisone dose. I might have done the same on many occasions. Unfortunately, increasing your prednisone dose won't get you off prednisone any sooner. Taking more prednisone will continue to suppress your adrenal function and make it harder to taper off.