I think there is a chance you might be coming down with depression. Usually when people sit alone by them seleves they get deep with in thought and start thinking about things they shouldn't think of. You just gotta push those thoughts out of your head before it does lead into depression. And remember this you are important and you do matter.
I am 11 years old and find myself sad randomly. I don't like it and I feel like I'm not important. Can someone tell me why this is happening?
Well you are a pre-teen and you're getting to that emotional age. Girls get this earlier than guys so that makes sense that you are getting it at 11. Maybe try talking to your parents about it or someone your really close too that will understand. Hope you'll overcome this situation :)
P.S. I'm 17 and been through this
Hi :3 When I was your age, I felt the same way. I always thought that I wasn't important and was feeling quite down often.
Try to find things that make you happy! I realized that I really liked to draw at that age and it really helped. Keep trying new things. Realize that there are many people out there who care for you a lot. Know that you are important too, even when you think you aren't.
If you need anymore help, feel free to talk to me over Blurtit, after what happened to me years ago I'm trying to help people who almost made the same mistakes I did.
Keep smiling :)