you say you have all these negative thoughts and things in your past and for someone that is 16 you must of been through some tough times,but you acknowledge you have and want to make your life better so that is the first stepping stone,i dont know your life story but you seem a strong willed person who wants better out of life and i admire you for sharing your feelings. keep strong. your young. and i truely wish you all the best out of life
I would suggest a Psychiatrist. Could be anxiety, could be mental illness.. no one will be able to diagnose you over the web. Try to stay away from caffeine and sugar and see if it helps any. If your already having problems like this, please don't use any illegal substances, it could make you worse.
I had racing thoughts about my past and disassociation like you, I ended up in the hospital 3 weeks later. Not trying to scare you, but definitely get it checked out.
therese83's suggestions are good. Although, if writing and talking doesn't help, try seeing your doctor about it. There is a small chance that these racing thoughts could be part of an underlying psychological condition (i.e. bipolar), and you're at the age when one is most likely to develop psychological conditions. I don't want to freak you out though, because that chance is very small, particularly if your racing thoughts are your only symptom. But good to check in any case. And also, a doctor could refer you on to a counsellor who could help you with strategies to control your thoughts, like the ones therese83 is suggesting. Try to find a counsellor who knows Cognitive-Behavioural Therapy (CBT), because it's the best at things like this.
Do you have someone to talk too.
It is so good to share these thoughts, to get them out, to go on and on to another person and then they don't seem so bad.
If not how about writing them down in a journal, this is particularly helpful at night before bed.
hugs