Hello~It sounds like low blood sugar, but to be safe, I would tell your folks and see your GP, if he/she thinks it is serious, he/she will probably order some tests or even refer you to a neurologist.
Could you have low blood sugar? That's how I feel when my blood sugar plummets. What happens if you eat something? Feel better? My son also has low blood sugar and he is aware of signs and eats something really quick to offset it. Otherwise, you should talk to your parents about this. No, you are not likely to be dying. And it is very doubtful you have high blood pressure at your young age. BP when high usually causes headache and floating things in your vision, not what you describe and frankly, is usually silent. However, my younger son had a summer of passing out due to dehydration, lack of eating properly so his doctor said it was orthostatic hypotension. NOT dangerous other than an injury from falling. Paying attention to his hydration, eating and having hi get up slowly has prevented it.