It's like in 7 to 7 months, he change's abruptly: to being the nicest and funniest guy ever, to being suicidal and breaking things, screaming and it really saddens and fears me, that one day he'll eventually kill himself, or even someone else. What's more unsetlling, even, is that today he made the shift to his bad self, but yesterday before sleep, he and my mother were laughing and cracking up jokes like never before. What reason could this behaviour have, and what should I, as their 15y/o son, do?
