Valentine's day seven weeks ago, when a mother should be so excited about her son coming home from middle school, bragging about how many cards he got or who his secret admirers might be. Instead she... See More
Valentine's day seven weeks ago, when a mother should be so excited about her son coming home from middle school, bragging about how many cards he got or who his secret admirers might be. Instead she got a 911 call that would plunge into an underground she could not imagine, teenagers looking for what's been called "The good kid" high. This week, I sat down with a moth moth mother. Three minutes. What can you do in three minutes? Listen to your favorite song. Because that's what happens if you play the choking game. Reporter: The choking game is all over the internet -- but it's not a game. But even after years of battling the problem and online awareness campaigns - - we're still seeing this. What looks like do it yourself videos on youtube. So today, I'm going to choke myself. Reporter: This boy climbs a makeshift gallows, seconds later, he is coughing and holding his throat. How did I miss this? Seriously, because apparently it's been around for a really, really long time. It seems insane to me that kids would choke themselves for fun. There you do, got it. Reporter: With a new baby, this should be a happy time for Kristina fields. She's an army mom. Her husband, Dana, is a soldier. Stationed at ft. Carson, Colorado, they're raising five children. But, next to the majesty of pike's peak in the rockies, a senseless tragedy. Six weeks ago, her oldest child, 13-year-old louie, is found on the floor of his middle school bathroom unconscious. His mother gets the call. I was like, "Is my son okay?" And there was a brief pause, but it was the longest pause. And she was like, "911's been called. We need you here right away." Reporter: They rush lie to the hospital but there is nothing they can do. And I just kept praying that I would just wake up because this is not real. Like, I just saw him this morning. I -- I gave him a hug and a kiss, and I sent him to school. You're supposed to come home from school. And I was like, what the hell happened? Like, what could happen at school? And they were like, "He hung himself with a belt." It was like -- like, it was just a Normal Friday thing to do. Like, okay. Reporter: The army says its investigation is still active. But the death certificate says it was suicide. And Kristina believed it, at first. But it was strange. Louie didn't seem depressed to her. He was grounded, but here he is in a home video, the night before he died, joking around as usual. We cannot move from this spot. Reporter: He didn't leave a note. And another odd detail from the day he died -- From what I was told from the investigators, he asked a friend to go with him to the bathroom. Reporter: To commit suicide? That's my exact question. Reporter: And then, the day of the funeral, Kristina finds a stunning voicemail on her phone. Its from louie. And when I scrolled down, I saw his name. And I was like, "What?" Reporter: A month before he died, louie had unknowingly pocket-dialed his mother. It's hard to hear, but Kristina says one terrifying telltale word jumps out - - "Choke." Choke me again. Reporter: Did you have any doubt in your mind after listening to that accidental voice message that that's what Louis was doing that day, that he and his friend were playing the choking game? Not after listening to that. I believe that that makes sense. Reporter: Why would anybody want to choke themselves? What on Earth is fun about it? It's the thrill of testing limits, of going to the edge. It's described as a euphoria. Reporter: It is sometimes called the "Good kid" high. It's typically what you see the happy kids do because they don't want to resort to drugs and alcohol. All these kids you hear, when you talk to their parents and their friends, they're happy kids, they're good kids. Reporter: One foundation estimates the total number of deaths at between 250 and 1000 a year, but no one really knows for sure. It seems like a no-brainer. Choking yourself is dangerous. Why don't they understand that. Right. Because they don't think that the really bad thing that might happen from choking -- Reporter: Death? Death will happen to them. Teenagers think they're invincible. Reporter: Back at fort Carson, tonight -- So this is louie's room. His bed is exactly the way it was when he left for school. Reporter: An unmade bed, an unfinished sketch book -- reminders of a boy who is never coming home. His family hoping their grief will serve as a warning. There are so many kids that are dying from this because they want to get that high, and they don't realize it by themselves how dangerous it is. If you think your kids are playing the choking game and want help, go to our website at abcnews.com for more resources. We want to know what you think about Kristina's story, tweet us by You are about to become very popular.
This transcript has been automatically generated and may not be 100% accurate.