Had that as well. Went to the ENT, he spoke about what he described as "little stones" in ones inner ear that get misaligned, he made me lie flat on the bed and just turn my head to the side, room would spin, he then did a few exercises with me, had me hanging off the bed to try and get the balance correct in the ear and told me to do the exercises at home, helped a lot. Although I still get transient attacks of vertigo when turning in bed, its def related to your ear, I would start with an ENT investigation.