About 4 Weeks Ago, The Basement Door Hit The Back

about 4 weeks ago, the basement door hit the back of my foot above the bone. It's healed some but still feel some stinging with certain movements. no pain while I'm standing. Riding bike is not a problem but have only been wearing sandals (shoes without a back). What do you think it might be and should I be putting heat or cold pack on it. Pretty sure it's not the achilles tendon. Thank you.