It seems from the history that you had a injury to the head about a year ago following which you had a lump. The lump is because of collection of blood in the layers is scalp as a result of trauma. Since you did not had symptoms like loss of consciousness
or bleeding from ear or nose there was probably no concussion injury
to the brain.
Dizziness is not related to head injury
hence it requires evaluation to find out the underlying cause and treatment accordingly.
The common causes for dizziness are hypovolemia
or decreased blood supply to brain as a result of carotid artery
Hence I advice you to consult your doctor for examination and treatment accordingly.