By Madison Williams The Carolina quarterback left Sunday’s game against the 49ers with a walking boot on his left foot. After the Panthers dropped to 1–4 with their 37–15 loss to the 49ers on Sunday, quarterback Baker Mayfield had X-rays on his left foot. The first-year Carolina starter wore a walking boot to his postgame press conference. He told reporters that he suffered a left ankle injury and that “it’s painful,” via The Charlotte Observer. However, NFL Network’s Ian Rapoport reported Monday that the X-rays were negative. Mayfield will undergo an MRI on Monday to determine the severity of…