Sudden outbreak (3-4 days) of sore spots on tongue, two sores on inside of cheeks, slightly sore throat. not sexually active. possible causes?

Stomatitis: The first event of cold sores, usually due to the family of herpes, in adults can be more symptomatic, more sores and more painful. You don't seem to have so many of them so it may not be primary event but observe and don't let yourself get dehydrated due to pain on swallowing, see your doctor when you can for proper treatment.

Many: Herpes, allergic reaction, response to gerd, canker sores, lichen planus, uri, many other reasons. You need to be physically examined to determine diagnosis and then course of treatment. Please call your dentist or physician for examination.