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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.
If your ringing ears are becoming a major issue, see a doctor. Anxiety rarely causes a persistent, long term ear ringing. There are ways that anxiety can contribute to chronic tinnitus, which we'll explain in a moment, but seeking out medical attention can help.