Oh I get that too but I call it my Heat Tree.... It goes up my back into my neck. Its almost a hot feeling. Its actually the adrenaline from the panic. Its your bodies natural reaction, it goes along with the panic attack. Totally get that too, that is how I know when I am really having a tough time.
They feel like fuzzy almost numb feelings and sometimes cause tingling. The burning almost feels like your on fire from the inside...it can be so intense you can't sit still.
Hi I suffer from anxiety and I get the same feelings however I have them all day everyday. I get them mostly in my lower legs and occasionally in my arms. If you know he has anxiety that's probably what's causing it but of course have him checked for Lyme Disease.