Hi Alan,
I'm thinking you should see your neuro. I went on azathioprine about 16 months ago and had no pain or any problems. My dose is higher than yours (150 mg daily taken in two 75 mg doses) but I think the dose is determined by your weight. I also had loads of bloodwork and it always came back normal. Anyways I just think that your reaction seems a bit extreme and it would certainly worry me. Hope everything else is good with you!
~Kathy