Regaining it is a bum deal. In working those minute and fragile muscles a lot of pain can result...
Your options are to find something squishy underfoot always or to rebuild the muscles. PT options are very limited in this area for some unknown reason.
I've found marbles.... about a dozen, on a tray to pick up between the toes and drop into a dish on same tray helps a lot. Start with one or two rounds of this each day and build up... Most other exercises did zip.
After I'd done this a couple of weeks, my feet HURT! But it went away AND I could actually FEEL more muscle tone in the feet, as long as I kept it up.
Remember start out very slowly 4-5 days at at time before you up the 'ante' so to speak. Going easy is safer and involves less pain.
Hope for the best and keep us up to date soon - j