I am a 55 year old woman. I have developed a buzzing in my head, not in my ears, but it seems generalized in the middle of my head. I have no history of tinitus, hypertension , or related problems. I have had a relatively frequent dull headache during this same time period. Historically I have had few headaches and just one migrain many years ago. No changes in visual acuity at this time. Any ideas?