With the symptoms you describe you should see your doctor and have your ears examined. The symptoms you are experiencing could be secondary to an ear infection. If that is the case, then antibiotics will be recommended and your symptoms would improve shortly thereafter. Grinding of your teeth can certainly cause an ear ache, but with a stuffy nose and sore throat infection seems likely. If your doctor is able to see in your ears and does not see an infection, then trying mouth guards at night to help with the grinding is recommended.
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No this is not consistent with a brain tumor.
You need not worry.
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