My jaw clicks really loud when I chew. Does this indicate lockjaw?

Tmj. Sounds like you may have some displacement of the soft tissue internal jaw joint structures. You should consult with your dentist.
TMJ Disorder likely. It sounds like you are experiencing temporomadibular joint disorder. This disorder can come and go throughout a lifetime or become constant. Signs of tmd are pain in the jaw, ear aches, headaches, popping and clicking, and can cause your jaw to lock. This condition is usually brought on by stress, however can develop overtime if your dental bite is not properly aligned. I suggest a prosthodontist.
Displaced TMJ Disc. Displaced TMJ disk. See a TMJ expert for advice. Any dentist can be a TMJ expert with the proper training and experience. Most commonly, oral surgeons, prosthodontists, and orofacial pain specialists. Ask your MD, your dentist and your dental society for referrals.
Movable disc. There is a disc in the temporomandibular joint (TMJ) that separates the lower jaw from the socket in the skull. If the disc or its ligaments are injured or stretched, the disc can 'pop' out of position during opening or closing. This makes a 'clicking' sound when it occurs. This is a temporomandibular joint disorder (tmj). A dentist can evaluate this problem and possibly correct it.