Sprained feet are not swollen but very painful, mostly refers to the pain after ankle sprain, the common causes are soft tissue injury, bone fracture, Achilles tendon injury and so on. 1. Soft tissue injury: sprain due to excessive flexion of the ankle joint can cause injury to muscles, tendons and other soft tissues, not necessarily swelling after the injury, but pain and other symptoms can occur. 2. Fracture: ankle sprain may cause fracture of the ankle joint, including the heel bone, tibia, fibula, etc. After the fracture, the broken end can cause pain by stimulating the surrounding tissues, and if there is no obvious damage to the surrounding tissues, there will be no obvious swelling. 3. Achilles tendon injury: If the Achilles tendon is damaged due to the force of the sprain, it can also cause pain in the ankle joint, and it may not necessarily show symptoms of obvious swelling. If the symptoms of sprained ankle pain continue to be unrelieved, it is recommended to consult a doctor in time and follow the doctor’s instructions for treatment.