There are lots of questions that I would like to ask to try and find out more about exactly what might be going on, and of course I would like to be able to examine you, however this is obviously not feasible. I am happy to give you my best guess as to what might have happened, but before I say anything I would recommend going to a dentist
, oral surgeon
, or ENT to be examined if this problem persists for more than a week or so. My best guess from what limited information I have is that you may have subluxed your TMJ (temporomandubular-joint, aka "jaw" joint). The TMJ is a fairly complex joint which has an articular disk which helps to separate the joints two separate functions. The lower portion of the joint is made up of the articular disc and the condyle of the mandible d is responsible for the rotation aspect of movement of the joint (which is what happens with mild/moderate mouth opening). The second (upper) portion of the joint is made up of the articular disk and the temporal bone (specifically the glenoid fossa) and is responsible for the translational aspect of movement in the joint (the sliding that occurs with very wide mouth opening). Subluxation of the joint means partial dislocation of a joint and "popping" back into place. This can be quite painful at times, and can cause some inflammation of the joint capsule which can cause abnormal joint function for a few days until the swelling goes away. Anti-inflammatories (like motrin) can help speed up this process. Again I would recommend getting evaluated by a dentist, ENT, or oral surgeon if you continue to have jaw problems for more than a week or two. I hope that this has been helpful.