It was sudden but a year before I had the full body senory symptoms, I developed a chronic itch on the small of my back and it was diagnosed as Notalgia Paresthetica.

Fortunately or unfortunately, the nerve symptoms (pins, needles, burning, numbness etc), the location of symptoms, and intensity are variable & eposodic. For example, the last few days, the senory symptoms are little noticeable and I don't need any meds but last week the symptoms were bad enough to need the Amitriptyline. The doc tells me that's not typical of PN. Also, while my symptoms tend to be most felt in hands & feet, they can occur anywhere including the scalp and back, and that I had a brain MRI.