Hello JY,
Thank you for your question. Is this the first time you are having this pain? Is the pain associated with any muscular pain like headaches or neck pain?
A recent event like a painful locked jaw and clicking joint is best treated as soon as possible, especially if it is hard to chew and function. Clicking can mean some disc displacement issue, which is a structural problem.
The TMJ (temporomandibular joint) could be pressing on the back of the disc (which is displaced). This area has nerve endings, thus causing pain on biting.
Pain worsening during morning and night time could mean other aspects are at play e.g. sleep bruxism, clenching or even tooth nerve pain. All these need to be excluded because TMJ pain and its disorders can be manifestations of many aspects of head and neck issues.
Sometimes, it could be as simple as a avoidance of chewing on food that requires much chewing to digest, or even pain killers as was suggested.
Soft diet and hot towel massage around the joint sometimes helps. And if it was any structural pathology, then an orthotic/splint/positioner might actually be used to provide relieve to the TMJ.
A thorough examination is crucial with considerations to function and pain relief. It's very tough for us to make a call without further understanding the symptoms and anatomy of your issue.
I know this is of not much help, but I hope it sheds some light on why you are suffering from the pain.
