An Morton's neuroma is a fairly common painful condition impacting the ball of the toe. In between the metatarsal bones in the pad of the toe, there are nerve endings, and these nerves could be swollen if squeezed in between those metatarsal heads. Due to this irritation, fibrosis tissue forms. https://articlebiz.com/article/1052308884-what-is-a-mortons-neuroma-in-the-foot