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Hi Sue, The ringing in the ears is called Tinnitus. It can be a side effect of medications (check what you are taking) or for me, it can also be a sign that a migraine is on the way. It could also mean a number of many other things, depending on other symptoms you may have.
What is also interesting however is that many people report that their tinnitus causes them extreme anxiety. The constant ear ringing provides a massive disruption of their ability to enjoy life, and in some cases can harm their ability to get sleep.