Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
I am not sure exactly what you mean by a continuous sound in your head. There are conditions called tinnitus that can produce a ringing in the ear(s) or a pulsatile sensation. The latter is a sound like a faint heartbeat. It may correspond with your own heartbeat. Pulsatile tinnitus has several causes that may include a vascular abnormality such as from an arterio-venous shunt, an arterial bruit like from carotid stenosis, or it can be a mechanical problem such as a spasm of the muscles in your mouth or in your ear.
Also, if your ear feels full like you are on an airplane, you may have a disorder of the eustachian tube itself. Common causes are allergies and colds. Other findings with this include dull hearing and possibly pain. It may occur when riding in elevators, going up a mountain in a car, etc.
I would suggest you discuss your symptoms with your primary care physician.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.