From the Runners World news article:
Thanks to the nature of our sport, we can suffer some painful foot conditions at times. One of the more common ones: the bunion. A bunion is an (often unsightly) protuberance at the base of your big toe. It forms when the metatarsophalangeal joint (MTP for short) is stressed over a prolonged period of time, causing the first metatarsal to turn outward and the big toe to point inward.
The resulting protrusion can be painful—especially when it chafes within shoes. Some people can also form a bunion at the base of the pinky toe, as well, known as a bunionette (and sometimes misdiagnosed as a Tailor’s bunion).
Read more at the link: https://www.runnersworld.com/health-injuries/a25345875/bunion-pain-relief/