I'm so sorry you've been going through this. I empathize. I've been on a 10+ year journey trying to get an accurate diagnosis for a variety of symptoms, including the lower leg ones you're experiencing. Last fall I went to see a movement disorder neurologist, due to other symptoms I was having, and she did a skin punch biopsy. That ruled out Parkinson's, thankfully, but it did show that I have small fiber neuropathy, which explains the numbness and tingling in my feet and lower legs (and now my hands as well).

I had had an EMG, but it turns out they don't pick up damage to the small fibers, only the larger ones. Using the skin biopsy results, combined with other tests and symptoms, I'm now exploring a broader diagnosis (e.g. autoimmune, dysautotomia, Ehlers-Danlos, POTS). There's a real shortage of doctors who truly understand how these diseases work, and specialists are going to specialize, but I'm determined to understand what's going on with my body.

Sometimes a precipitating event—from an accident or surgery to a fall or a horrible plane ride—can trigger the kind of symptoms you've been experiencing. Some of my symptoms showed up after I had shoulder surgery; others have been problems for me since childhood, but I never saw them as a part of a systemic disorder/disease.

Because my primary care physicians haven't been familiar with the disorders I mentioned above, and the standard tests have looked "normal" for the most part, I've had to do a lot of research on my own. I stick to well-vetted medical sites (Mayo, Cleveland Clinic, Hopkins, NIH, etc) and often have to seek out my own specialists, but I'm determined to find what's causing the symptoms, not just medicate them. One important reason for finding the cause is that treatment of symptoms varies depending on the diagnosis—e.g., opioids don't usually help with the fibromyalgia, certain kinds of exercise can exacerbate POTS tachycardia. Also, certain drugs work for some and not for others: I can't take pregabalin or gabapentin but have had good luck with duloxetine and low-dose naltrexone; others have had the opposite experiences.

I know this is a long post, but I hope it's helpful. Here are a couple of links for small fiber neuropathy that have really helped me.

Cleveland Clinic:
https://my.clevelandclinic.org/health/diseases/17479-small-fiber-neuropathy
Anne Louise Oaklander at Mass General (I love this video! Oaklander is not only a valued expert in the field but a great presenter:

Keep us posted on how you're doing. Let me know if you any questions about my post. Take care.