I have pain in the left side of my head and a ringing in my ears.

Headache: Hi I'm not sure how long this has being going on, and if you have other associated symptoms. But from the limited information, this can be a migraine (one sided headache, associated with tinnitus, or ringing in the ear). if you have severe dizziness or nausea, fever, blurry vision, you should see a doctor immediately. Otherwise, you can try excedrine or ibuprofen for migraine.