What kind of injection is it - cortisone? I would try wearing a mouth guard and applying ice and moist heated -what ever helps best. Figure out it your teeth are in alignment and visit a physiotherapist who will teach you gentle stretching exercises. Concentrate on keeping your jaw relaxed and be aware of your posture. Most people keep alot of tension in their jaw during the day. Take note of what foods trigger the attacks. I had alot of problems with TMJ and had to have braces and jaw surgery. I only get it occasionally now. I also have this accupuncture device which sends a battery operated stinging sensation and it helps tremendously in relaxing the muscles of the jaw.