Muscle spasms: Tinnitus that is described as clicking may be due to abnormalities that cause the muscle in the roof of the mouth (palate) to go into spasm. This causes the Eustachian tube, which helps equalize pressure in the ears, to repeatedly open and close. Multiple sclerosis and other neurologic diseases that are associated with muscle spasms may also be a cause of tinnitus, as they may lead to spasms of certain muscles in the middle ear that can cause the repetitive clicking.
Vascular issues. Some people have blood vessels near their ears that are capable of causing tinnitus. I have found that if the blood pressure is elevated, this increased pressure can cause that dreaded ringing in your ears or even a whooshing sound. Because pregnant women often have elevated blood pressure, they are easily susceptible to tinnitus. Tinnitus caused by pregnancy should go away with an over the counter tinnitus treatment and once the baby is born. An overactive thyroid has also been shown to causes vascular issues that bring on tinnitus.
Atherosclerosis. With age and buildup of cholesterol and other deposits, major blood vessels close to your middle and inner ear lose some of their elasticity — the ability to flex or expand slightly with each heartbeat. That causes blood flow to become more forceful, making it easier for your ear to detect the beats. You can generally hear this type of tinnitus in both ears.