You sound similar to what happened to me. Came on nearly overnight but mine started with pain in the toes like I had walked on hot rocks, and some foot swelling. Went to the Neruo and he feels I have a pinched nerve in my back. If you have back problems, that will probably be your diagnosis as well.

I highly recommend you look at the posts for the B12 suppliments and get one. After I saw the neuro I bumped my intake of the suppliment (he recommended B12, B6 and Folic) and almost overnight my feet felt better. Hoping that continues.

Best of luck to you. I hope the MRI finds something amiss. That sounds horrible to say but at least then you know what is up vs. unknown reason for PN.

dave