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There are a number of things that can cause a "weird" taste in your mouth and/or bad breath. Many of them involve the teeth, gums, tongue, salivary glands or throat. Since you have recently seen a DDS and been given a clean bill of health in this area then we have to think about other conditions.
Up to one in 10 cases of bad breath or taste comes not from the mouth but rather from a systemic
condition. Some conditions, such as diabetes, kidney failure, liver disease, chronic stomach reflux (GERD), sinus infections, and even cancer cause be the culprit. Even smoking or chewing tobacco can contribute to these issues.
Since you have been suffering with this condition for so long I suggest you consult with a physician who has an open mind about your complaint and who can help you to rule out any of these systemic issues.
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