What Causes Lack Of Libido While On Axiron Pumps?

I have been taking axeron 2 pumps for 3 years and my level was like 630 or so. started having trouble with sex. And dr check my and my level had dropped to 300 something. And he told me to go to 4 pumps and also had a MRI done on my head to check my pitutary. I still have two month before I go back. I have been on the 4 pumps for a month but it has not help. Whats up?