Ear ringing can be caused by sinus congestion, where your nose gets so plugged that you have to breath through your mouth. What happens is that the sinus openings and or the eustachian tubes get blocked with mucous. This blockage of the nose and eustachian tubes can cause Tinnitus or ringing of the ears. The congestion can be caused by allergies, so a person should be tested by an allergy specialist. Once you find out if you are allergic to anything, you will need to avoid that food or substance. If the sinus congestion clears up, your ringing ears should at least improve. If your Tinnitus continues, there is probably another cause, and your search for a solution will have to continue.