I have had a bad sinus infection for a few months now i went to the dentist and had this tooth xrayd a few months ago and it was fine. Now today i went to the dentist had him xray this tooth and the sinus looks like it's down toward the gumline. He said this tooth is not abscessed but it does have decay and needs a filling. I'm worried about the sinus pushing down. Is this due to overflossing or are my sinuses badly infected? I have been draining yellow mucus for a while now wondering if i should start back an antibiotic.

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