Most people feel better in a few hours or, in some cases, a few days. It continued to worsen day by day until holding a reg in your mouth became an exercise in agony. For most divers, a few days without the strain of holding a reg in their mouth is usually enough for the joint to return to normal. But if the pain continues even when you aren't on a dive vacation, chances are that a congenital deformity, trauma, or clenching your teeth while sleeping may be the culprit. In the case of unresolved pain, you should consult your physician.
Several companies make alternatives to conventional mouthpieces.
One of the most popular is SeaCure's moldable mouthpiece that allows you to customize it exactly to your bite. You can find it in most dive stores. The Comfo-Bite from Aqua Lung doesn't require you to bite down as hard as conventional mouthpieces. Our ScubaLab tests have shown it to work well for many divers, but not all. Multidirectional swivels on the regulator first stage can help.