Nervous about telling teachers if I am ill?

Ok. So I often feel dizzy and sometimes faint, but if it happens at school, I feel nervous about telling the teacher. I don't know why, but i'm always sscared about what they will do, ask etc. A few weeks ago, i felt ill and told, but I was just so nervous when I was talking to the teacher. Any help. I was, and still am a bit, feeling ill today and was so scared I just said I was hot.

I also hate telling my parents, not as much as teachers coz I know how my mum deals with it. Any advice. Also, can anyone tell me what teachers do if you feel, or do, faint? I've felt faint once but i've moved schools since then and i'm not sure what happens at my new school.