On and Off

So lately I haven't been feeling right, not sick like, but more so depressed. It just seems like everything that is going on around me is moving so fast and I'm being left behind. Sometimes when I'm sitting in class, not really doing anything I'll feel this sad feeling come over me. I'm not really sure why, but during that time I tend to just think about the negatives in my life, and I start to put myself down. It doesn't seem like anything serious because 5 or 10 minutes later I'll start to feel okay again, but it soon returns. I don't fully understand what's going on or why, but this has been happening a lot lately, and it used to never happen. It's really starting to bother me. I think about how no one is taking me seriously when it comes to my plans for the future and my life goal, it seems like they are all laughing in my face, and that's one thing I do not appreciate. This has led to me getting less and less sleep, which leads to me not focusing in school, which is definitely not a good thing. I've come to wonder if maybe this is just a stage I'm going through, but if so, then it doesn't seem like a normal one. I'm trying to focus on my guitar and drum lessons, and I'm getting excited for that, but at the same time I can't fully put my all into it and it's driving me insane. I've tried talking to some people about it but they just laugh or don't understand. I don't know what I'm going through, that keeps going on and off but I hope it ends soon. I really need it to.