After exercising, the heels

It used to be fine, but lately my heels feel too hard after exercising.

It's starting to crack, so I'm upset.

It doesn't just look that way; the skin feels hard to the touch, and I even feel stiffness if I put weight on my foot for a long time. I usually massage my feet with lotion after exercising, but there is no sign of improvement. Is there a good solution?