Much of your history is similar to mine. Severe Carpal Tunnel during pregnancy etc.

Mine turned out to be a thyroid problem, which masqueraded as normal for several years. But in reality I was hypo for a long time. After thyroid supplementation I had a vast improvement in the hands and esp. the feet.
I had such pain in my feet-- !!

People with hypothyroidism deposit a substance in the carpal and tarsal tunnels which pinches off the nerves. My blood work was only minor but a technicium scan revealed a damaged gland and I had a right sided goiter. The doctor said it was "idiopathic" meaning he didn't understand it.

So I'd get a very good doctor who is experienced in thyroid treatment.

Many of the newer treadmills have cushioning, but I still find them painful as well. The smaller newer ellipticals are much easier on the feet and hips.