What Causes Dizziness And Lightheadedness After An Injury?

about jan 18, i hit the left side of my forhead on the bathtub while i slipped getting out of tub.took a few days before bruise appear. was sore to touch for a few weeks. bruise lasted for a month or so.i have been haveing dizzyness, lightheaded,off balance.could this be serious?also fall asleep in my chair once or twice a day.