What causes a buzzing sound like something buzzing by ear?

Tinnitus occurs when you experience ringing or other noises in your ears & isn't caused by external sounds. Tinnitus is generally caused by an underlying condition such as age-associated hearing loss, infection, meds, an injury to the ear or a circulatory system problem. Tinnitus improves with treatment of the underlying cause. You should therefore be examined by a physician as soon as possible!

Tinnitus or ringing/hearing noise in the ear is a poorly understood condition, sometimes with easily treatable causes, some other times difficult to treat if it involves damage to the inner ear. Start with your primary care doc who can further coordinate a thorough ENT evaluation as needed. Keep a log of your symptoms with circumstances possibly triggering them.