In general, pain that persists for such a long time needs to be seen by a physician in person. There are many things that could cause this sort of persistent pain, but the common and simple things will usually go away by themselves. You don't mention what makes the pain better or worse, and what you have tried in the past. You also don't mention your past medical history, family history, and whether or not you have had any surgeries or other issues with the area that is bothering you now. Because of that, we'll just cover some general ideas.
The phrase "lock up" seems to imply some sort of musculoskeletal complaint. These can often become nagging problems, as inflammation in one area often begets more inflammation. If an over the counter non-steroidal anti-inflammatory (NSAID) has not helped, than that makes this option less likely. Another thought related to the location would be temporomandibular joint dysfunction syndrome, or TMJ, due to problems with your jaw itself. The fact that you mention generalized discomfort and stiffness, however, lead me to believe that there might be something more going on here. Please see your physician for more guidance, and your primary care physician
might be a great place to start.