Hi streetnfish,
Ringing in the ears is called tinnitus. This is a term used to describe the sensation of ringing, roaring, low-pitched hissing, chirping, screeching, or even musical sounds when such sounds are not externally present.
Tinnitus can be caused by a wide variety of events, such as certain drugs, wax in the ear canal, exposure to loud noises, tears in various membranes within the ear, or damage to the acoustic nerve itself. It can be temporary or permanent. In the latter case, treatment of the condition is not as effective as medicine would like.
Tinnitus & a sensation of fullness or plugging can & do result from damage to the ear secondary to improper clearing/equalization while diving.
The cause & possible treatment of persistent symptoms is best determined by a physician expert in disorders of the ear, known as an ENT. Those not having an ENT can start by seeing their regular doctor, and s/he can make a specialist referral if required.
Until all symptoms of an ear disorder have resolved, or clearance to dive is obtained from a qualified physician, it is prudent to refrain from scuba.
This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual, and should not be construed as such.
Best of luck.
DocVikingo