I have had mild numbness in my left cheek on and off for several weeks now. have also had tension headaches?

Possible TMJ/clench : Sometimes you can get symptoms like this from profound clenching (from both daytime or night time clenching). Profound clenching can set off headaches as well. Most people underestimate how many headaches start from a dental cause. But, any numbness needs follow up now. You could have a neurologic problem and i would not delay having it evaluated. An oral surgeon is a great place to start.

Concern: When patients discuss numbness in the face, i usually want to see that patient asap. It could be an infected upper tooth, tmj/tmd, some neurological source or some other cause. Need a good history and exam. Don't hesitate since it had been several weks now.