I Noticed Bruising On My Left Foot, No Injury After

I noticed bruising on my left foot, no injury after standing with my foot turned. When I placed my foot flat on the floor, I felt something like an object on the corner. Sometimes I walk around outside barefoot, but I don't recall stepping on anything to call a break in my skin, There's no pain, just discoloration, a small spot on the bottom and about a 2" spot on the corner, near the small toe. I soaked in Epsom salt, no change to my foot,