I had looked at Myotonic dystrophy, and am obviously crossing my fingers that this is not the issue! :-)
After your suggestion of neuromyotonia, I did some research and it actually seems to fit the bill perfectly, even explains the excessive sweating I was getting but didn't think was related.
I will talk with my GP about this possibility next week, and then the neurologist. Just need to be careful how I go about it with the neurologist as most specialists don't like to be wrong. :-)
Obviously time will tell, and I will come back with an update. I just want to thank you so very, very much Jan, I have been going through this for years with no diagnosis, and even though the neurologists were heading into the right direction, after some research I could see that myotonia congenita didn't match what I was going through.
After researching neuromyotonia, and how it fitted my symptoms, I feel I have a much better direction to take for a conclusive diagnosis. Considering the extreme rarity of the Isaac Syndrome, I think your suggested diagnoses are a testament to your knowledge in this area, and I think this community is lucky to have someone such as yourself here.
Thanks again, and I will be sure to post back in the coming months on my outcomes.