I am by no means a back expert. This is just my personal experience with this issue.
I'm sure your mom used to see you in front of the tv and kept telling you to sit straight. The truth is, getting comfortable while playing video games is essential. A long run is always better on a comfy couch, chair or a bean bag. Sitting properly is equally as important if not more. Since I work full time as a web developer, it is particularly relevant. For the longest time, I was slouching for hours in front of a tv or a computer. Sitting in a bad posture for so long might take its toll on your back one day, and you're not gonna like it. Case in proof, I am a 23 years old man dealing with back pain.
You might say: "Get more active! This is your fault for not taking care of it!" This is partially true. See, I play table tennis on a regular basis. I'm talking out of breath, running like a mad man type of table tennis. Being active or fit is not the problem, but rather the muscles I'm not using are not active enough. Muscle imbalance is where one muscle compensates for the opposite one's lack of strength. Your back is the center of all this. It's not just your back, it's your whole body that needs to be balanced.
In regards to relief, it sometimes takes more than just a few back stretches to cure the pain for good. You need to know a few things:
Back pain is usually not a result of a sudden injury, like lifting with your back. Your bad posture habits or any stress you inflict on your back will build up micro damage overtime. That one bad movement pushes it over the edge.
You do some back streches, you feel better. That's what a lot of specialists make you do. They fix where the pain occurs. What if your legs need reinforcement too, and it's affecting your back? How would you know? I had a friend who had back pain for the longest time. He just needed orthopedic shoes because one of his legs was shorter by a few millimeters. I would recommend going to a specialist, like a physiotherapist, chiropractor, or osteopath. Ask for a head to toe assessment. There may be more things to fix than you realize.
Recovery will take time, be very patient. The important part is to keep doing the exercise that you've been told to do. Even beyond recovery you should continue. You don't want a relapse. It's gonna be much worse. Don't let it get chronic, cause you're screwed once that happens.
In my case, posture is the big culprit. Ergonomically, I need to fix my work environment. My bad habits at home needs to be fixed as well. It gets tiring keeping that straight posture all day. Why can't it go away while I relax? I associate relaxing with slouching, that's the problem. I need to program a healthy posture into my everyday life. I take breaks from playing every hour to stretch, and it helps.
The internet will give you the necessary knowledge you need to start treating your pain. Get as much information as you can. Then, go see a specialist based on what you learned. Ask him about techniques you read about. The more info you get, the easier it will be to know exactly what to fix. Knowing is half the battle.
In relation to games, this issue affects my portable gaming mostly. I can still play my home consoles if I sit correctly. I did stop playing my ds and psp. I simply cannot hold the machine and look down without my back hurting. No need to say that a 3DS is not an option at this point.
It's not many people who will develop back pain. But if you deal with it, you can't let it go away on its own, it just won't. Or if it does, the lack of prevention will make it come back stronger. I'm at the point where I'm getting on top of it with specialists and exercices. I'm also lucky to have insurance with my company. Spending 80$ per hour is crazy. It might take 3 months. It might take 6. But I don't plan to stay crippled for the rest of my life.
So, that new Legend of Zelda on the 3DS
looks pretty amazing, huh? ;_;