Painful skin spots on the bottom of the foot, whether below the heel, arch, or ball of the foot may be several different things. There is a tendency to call most skin "things" on the bottom of the foot a WART.. While there may be some merit to that , in some cases, it couldn't be farther from the truth.
A wart is a VIRUS infection of the outer layer (epidermis) of the skin ONLY. It does not have tentacles or "roots" but often feels deep. Warts begin when the papilloma virus enters the skin by exposure or injury or scraping, and spreads within the skin causing a plug. This may cause thickened skin over the wart. The wart may enlarge, spread, appear as cauliflower or other patterns.
Other "things" that can cause skin changes with or without pain in the bottom of the foot? Walking barefoot at home can pick up pieces or hair or dirt or other things that penetrate the skin sometimes WITHOUT discomfort forming a small inclusion CYST. Sweat ducts may plug up forming a core or porokeratosis. Calluses under areas of excessive pressure may get deep plugs or NUCLEI within them. Blisters from friction may fill with fluid, and possibly get infected especially in diabetics. Certain skin cancers such as squamous cell or melanoma may cause spots in the skin that may resemble warts. INJURY to the skin from punctures or scrapes may cause WARTS to form.
So, skin "warts" on the foot may NOT be what they seem !
Proper diagnosis and treatment of that "thing under my foot" by a foot specialist, sometimes by skin biopsy, is important for patient safety and to select the proper treatment. Is that a wart? Maybe.