try some Dr. Scholls Tri Comfort insoles. My internist recommended them several year ago and I have pairs in all my shoes. also or walking my podiatrist approved of my walking shoe choice. I buy roomy slip ones with tubular bottoms. K-Swiss and Sketchers make some. The more cushion on the sole the better.
I have those inserts in all my shoes. Wouldn’t even have been able to walk without them for the last ten years. (Heel pain, back pain, and pain on ball of foot - all got better with different shoes, and inserts).
This is new problem. I think it may be neuropathy. It doesn’t seem to matter whether I am walking, standing, or sitting.