Determine the cause of the tinnitus by seeing your doctor for a proper diagnosis. The list of causes is extensive and includes head injury, vascular problems, ear infections, tumors, loud noise, hearing loss and the side effects of medications. The treatment for tinnitus depends on the cause. Note that since some medications can cause tinnitus, the doctor may also check for this and change your prescription accordingly.

If I were you I would look on the internet for a forum about this ( ask questions there ) that a specialist can help you with.Ask your Doc to refer you to a ENT again, a different one.

I suffered from this for many years and the more I went to the doctor, the more medications got prescribed and the louder the sound got. What helped me was to get off all prescribed meds. I started detoxing my body and found some natural remedies and the ringing in my ear has stopped!

I am now a firm believer in trying natural cures to get relief. You may want to give it a try to cure ringing ears.