Why do I have pain/soreness in my gum and cheek?

It's hard to pinpoint the source of the pain (tooth etc). Both my gum and up into my cheek hurt. It hurts to smile wide, laugh or even open my mouth wide. It also hurts to chew. The pain is probably a 5 on a scale of 1 to 10. It almost feels like I pulled a muscle but I'm not sure how that would have happened. Any ideas?