Calluses are caused by shear of shoes or pressure spots on the bottom or sides of the feet.
Your doctor will address what is the cause of these calluses and determine the best treatment plan for you. The provider can shave down the callus or determine ways to decrease the pressure on those areas. This may be done by orthotics and/or pads for the feet. They may also prescribe creams to help decrease the callus build up.
These look similar to pinpoint calluses or a small “seed corn” but can cause a significant amount of pain. It may feel like you are walking on a pebble. The cause of these is not completely known but may be caused by a clogged sweat gland or a small puncture to the skin making it grow inward with a core of callus.
https://www.podiatrytoday.com/when-runner-presents-painful-plantar-lesions
These may be treated by shaving/coring out the lesion, however this may not make it go away. To eliminate these lesions your doctor may apply prescription strength topical cantharone/salyclyic acid. Learn more about acid aftercare instructions.