Pain while chewing usually means the tooth is under stress. That stress may come from a cracked tooth, a cavity, an infection, a loose filling, or even clenching and grinding.
The location and timing of the pain help us narrow down the cause, but an exam is the best way to know for sure.
If chewing is painful, try eating on the opposite side until you’re seen. Continuing to chew on a damaged tooth may make the problem worse.