My son when playing video games stretches his neck toward the tv. its a habit. because of this an area in his back hurts. treatment? what's it called?

Neck strain: He may have strained his neck/back due to bad posture. This is quite common this day an age due to all the devices we use like computers, cell phones etc. He will benefit from physical therapy and proactively in the future should work on posture to prevent this from re-occuring

Muscle strain: make sure he is sitting in a well- supported position when playing games and limit game playing to no more than 1/2 hour a day there are many studies showing side affects of prolonged video game use