Welcome tj71, but sorry you're here.

I don't have any great advice on helping get to the bottom of things, but I do have some advice on the blood sugar thing having been through that aspect of it.

There's no debate that high blood sugar is an insult to nerves, but no one knows for sure at what point the damage starts occurring. After much reading and research, the only number I found referenced was 140. My response to that was modify my diet to keep my post-meal glucose under that to be safe. I actually try for 120. I don't think blood sugar is the cause of my neuropathy, but spiking it the way I was when I ate a lot of carbs certainly wasn't helping the matter.

Hope you have some luck finding the cause soon.