Thanks for your query, I have gone through your query. The lock jaw can be because of the TMJ Disorders like disc displacement without reduction or TMJ ankylosis or Oral submucous fibrosis. Consult a oral physician and get it evaluated. You need to take a radiograph like OPG and TMJ views, and alos you need to get an MRI to see the status of the disc. If it is a disc displacement, we can treat with piroxicam tablets 20mg twice daily on first day and once daily on the next 6days. Follow soft diet. If it is ankylosis, then it has to be treated surgically. If it is OSMF, then it has to be treated by intralesional injections or surgery. I hope my answer will help you, take care.