When I stand up after sitting for a reasonable amount of time I can take about five steps then I get very dizzy, start to shake and begin to blackout. This last about 10 seconds. I start to see stars when I get up sometimes but nothing to this severity. It has happened to me 6 times today. I started expecting it to happen to one of the times i tried to brace myself on a wall but the shaking caused my head to slam into the wall. I don't know what is going on.
I am a 16 year old girl. My work load is very heavy, not leaving much time for sleep and got about 3 hours of it last night. I am on Adderall for ADHD and drink a lot of coffee if that might have something to do with it.
Something else to note is that my jaw began to shake like I was shivering for about 20 minutes before my blackouts began.
What is happening to me?