It could possibly be from another tooth. The nerves sometimes send the wrong message to your brain, and thus you can get a pain in a completely different tooth to the one that has the problem.
However this doesn’t normally happen on opposite sides of the mouth, as the nerves on each side are separate. It could be a tooth directly above or below, or maybe right next to the painful one, that is actually the problem causer.
Your dentist should check all of your teeth if you are having recurring toothache, as there will be some reason.
Another reason of course, is you may have exposed part of the root of the tooth by over brushing, which can cause pain or sensitivity. If you have got into the habit of brushing your teeth too much, try just brushing your teeth in the morning and evening, and use mouthwash if your teeth feel unclean throughout the day.
I hope I could help!

You could have eaten something which ‘got stuck’ and sensitized the area, then brushed/flossed it away by the time you seen the dentist. However if it persists or worsens, this could be the early warning signs that you might need a root canal in that tooth.
Use Senodyne toothpaste for a week or two and see if it goes away.
Good Luck

Yes…I had the same thing a few years ago. Finally found out it was not the tooth, which
was sound. It was a nerve around the tooth that had somehow been irritated and was causing the pain.

yea its possible it could just be that you got hit by something in the mouth area