Left jaw pain?

Many things: Heart attack, impacted wisdom tooth, TMJ dysfunction, ear infection, muscle spasm, deep cavity in a tooth or into the nerve, poor sleeping position, your a boxer, etc.

Abscess or Grinding: Your jaw pain could be developing from a nerve in a tooth dying (becoming necrotic) and starting an infection (abscess), or it can be from grinding your teeth. If the pain usually occurs in the morning when you first awake, it is most likely from grinding. If the pain is constant or comes on randomly during the day, it is probably an infection. Could be wisdoms as well. See your dentist asap.

Need more info...: Like type of pain, what causes it, how long it lasts, exactly where it is centered, as well as radiographs of that region. Putting all of this information together, a local dentist can diagnose your oral health and determine if any of your teeth are suspect. Only then will you know what is wrong. Make the call.

More information: is needed in order to answer your question. Respectfully.

Many things: Many things. Jaw joint pain (TMJ), dental pain, bruxism, heart problem,, nerve problem (trigeminal neuralgia) or other problems. Need evaluation. Start with dentist. If teeth ok, he may refer you to orofacial pain expert. Good luck.