What would cause side of tongue to be sore and have white spots?

Hard to Say: Do you have a habit of biting your tongue? Did you traumatize that side of your tongue recently? How long has this been going on? It can be trauma, oral cancer, auto-immune disease (ie. Erosive lichen planus), etc... See your dentist soon for an evaluation.

Several things: Most common is trauma - biting the tongue others include: macroglossia or overly large tongue - similar to trama cancer candidiasis please go to a dentist asap for diagnosis.