A 42-year-old patient complains about acute pain in the region of the left temporomandibular joint (TMJ) that irradiates to the ear; headache, general indisposition, impossible mastication and limited mouth opening. Objectively: the patient's face is asymmetric due to the edema in the region of the left temporomandibular joint. The skin in this region is hyperemic. The pain is made worse by the smallest movements of mandible. Palpation of the joint causes acute pain. Mouth opening is limited down to 15-20 mm. What is the most likely diagnosis?