Tonsils are sore but no other bodily symptoms. What might be causing it?

Tonsillitis. You are probably starting to get an infection in your tonsils. Viruses are the commonest cause, but bacteria can also cause it, and even yeast can. If you develop a fever and aching, or if the pain becomes severe or does not improve in a day or two on its own, you will want to see a doc. Untreated strep can lead to rheumatic fever, which can cause permanent heart damage. That's your biggest risk.