What Causes Severe Pain On The Ankle Bone?

the back part of my ankle, right on the bone and around the bone on my left foot is so painful when there is pressure on it. Even wearing trainers becomes agony after an hour or so if it rubs against it,. It started a few months ago when i had a fall and a bike fell on my foot so i thought it was just buised but it hasn't gotten any better. If I'm not wearing shoes it's ok but the minute i put any kind of pressure or shoe or do exercise it starts hurting again