There must be a haematoma formation. I will advise you to get a CT Scan head done which will give a clear picture about if there is any kind of fracture or just the accumulation of blood. Consult a Neurologist for this and follow his advice. Is there is any kind of deficit then the treatment should be started immediately or it will be very difficult to treat at a latest stage.
Next Steps
consult a neurologist and get a CT SCAN head done
Health Tips
do not touch the dent again and again