I was dealing with tinnitis myself and still do occasionally. It has been an ongoing battle for me. I have sinus allergies as well as a bout of sinusitis and when they get a whiff of something that's on the bad list, I'd feel a bit more irritation and then an increase in the ringing.
I am no dr but I think that the inflammation of the sinus including the eustachian tube, which can travel to the inner ear due to whatever the cause, can bring this ringing on.
Something important that I experienced was, that a tooth infection can be missed by both the dr and dentist leading to a sinus infection. This caused problems for years. When this was finally dealt with due to my persistance, and finally anger (it was messing with my ability to listen to music), the headaches and ringing again slowly dissapeared.
