It only happens when i lay on my right side. note i hit my head a few weeks ago. the dizziness went away but it's been happening again in the past few days?

I positional vertigo: Vertigo or spinning sensation brought on by head or body movement is characteristic of an inner ear disorder. A tiny concretion in the inner ear that moved out of place is often the culprit. The head injury is probably unrelated. Treatment consists of meclizine tablets or head manipulations by an Otolaryngologist. Your physician can examine and advise you.