Lightheadedness with buzzing sound in my ears when i stand to walk--what is that?

Circulation issue: Most likely you're having a problem with circulation to the brain and/or inner ear. Antihypertensive medications and hardening of the arteries o the brain are the most common causes for this. Check your blood pressure when sitting & then when standing. If your blood pressure drops more than 20 points you have circulatory issues. Other causes relate to the auditory system. If so, consider ENT eval.