My Wife Started Feeling Discomfort On The Roof Of Her

My wife started feeling discomfort on the roof of her mouth 3 days ago. She didn't recall eating anything hot or sharp. The discomfort hasn't gone away since then, and we noticed today in looking inside her mouth that she has a spot (slightly smaller than a dime) where she's feeling the discomfort and it has a bright red ring around it. She isn't feeling any other symptoms (sore throat, fever, cold/flu). We are wondering if she should see a doctor or a dentist.