Temporary TMJ possible ?

About 6 weeks ago, my son was involved in an altercation that resulted in a couple of blows to his left cheekbone. He says at the time he felt some pain on the opposite (left) side but then it was OK until 5 days later when he began to experience quite severe pain just in front of his left ear (tmj joint?) This lasted for a week or so, then went away; however, a month ago it came back, and he now has a constant dull ache in the area and an earache, sometimes with sharp pain when he yawns or chews. He doesn't seem to have any difficulty opening his mouth, nor does he experience any clicking. He saw his MD, who says there is no ear infection or fracture but that it may be TMJ, so he should see his dentist if 10 days of ice/moist heat, gentle exercise, and advil didn't do the trick.

My question is: if this was caused by trauma to the opposite side of his cheek, will this be temporary? If so, how long should it last? He is unemployed and therefore has no insurance so doesn't want to go to the expense of having dental appliances made, if this might go away of its own accord. On the other hand, he has been suffering from major depression and anxiety, which causes him to tense up his facial muscles, so could this be the cause of the pain ... and maybe its just coincidental that it flared up a few days after the blows to the face?

Your opinion/advice would be greatly appreciated.

Thanks