I just happened upon this thread and it has been so helpful. I feel like a medical mystery sometimes. I too have had pins and needles in my left leg, now moving to my right leg. Often I have muscle tightness in all extremities when I try to get out of bed in the morning - when I start to walk it feels like I'm the Tin Man from the Wizard of Oz. Thankfully once I'm up and moving it gets better. At times I get chest tightness and difficulty breathing which is scary but I check my pulse ox, which is always normal which helps me not to panic. I've had a very thorough workup from eight or nine specialists including a Johns Hopkins Neurologist. At one point the diagnosis was SFPN, non-length dependent, but the skin biopsies were negative. We have also been puzzled because my symptoms vary markedly. In June my balance was bad and I needed a hiking pole to walk, had vertigo and chest palpitations, by November those symptoms were gone, then in mid-December I started again with the muscle tightness/spasms and burning at night that has made me feel like I'm being electrocuted. My neurologist thinks that it could be a post-viral reaction to COVID (in 2021) or a reaction to the Moderna COVID vaccine. I had Pfizer vaccines three or four times without difficulty, then I had two Moderna vaccines and this whole nightmare started. Or his other theory (also the opinion of the allergist) is that COVID kicked my immune system into overdrive which exacerbated my reaction to the Moderna vaccine. My immune system is so wacky now that I can't even tolerate vitamin supplements (riboflavin, magnesium, multi-vitamin, calcium send me out of my mind with itching/burning at night) and I can't tolerate sulfites and preservatives in food. So - long story short - it's helpful to read other people's experiences so I know I'm not crazy. Thanks everyone for posting!