I used to have pins and needles and numbness in both my feet for a lot of years (ten-ish) and still get it occasionally depending on what I am doing, sitting slouching for example stretching the lower back and SIJs. The nerves to the feet and mainly from the sciatic nerve. So if you have a problem in the L4-S3 area then you can have pins and needles and numbness in the feet from that. When these joints were subluxed it gave me the symptoms in my feet. I've also had injections in my lower back which made the muscles in my feet twitch. Also if your feet are pronated or lax, then that can also stretch the nerves and could explain trouble standing. I haven't found any doctor who knows or cares about numbness or pins and needles.
Joint group leader for South Central (Bucks, Oxon, Herts)