Why won't my throat soreness go away?

Last night around seven my throat felt sore a bit but I thought it was just dryness so I drank water then it felt better . When I went to bed I couldn't even fall asleep because the pain was so bad . Btw the pain is just on one side of the throat. I opened my mouth and looked at it in a mirror and my tonsills look normal. So what's wrong it still hurts