A great way to help reduce TMJ pain is to release the muscles and increase mobility. Do these simple exercises every morning and at night before going to bed. Make sure you also wear your night guard/splint at night.
Release the muscles
Reach over with one hand, pull up on the scalp, and slide the other hand down. Hold and wait for pain to decrease, and hold for 30 seconds. Move down along the jaw and repeat.
Increase the mobility
Put your tongue on the roof of your mouth, and open as wide as you can. Make sure your tongue is touching the palate while doing it, and hold it for 30 seconds.