I sometimes black out when I stand up...?

When I wake up on some days I feel normal. Then I stand up and I get dizzy and I don't p out I just have this black "cloud" that slowly creeps in closing up my vision. When it ends (in a few seconds) I usually feel normal once I sit/lay back down but sometimes even a few hours after I wake up, it still happens... And I know you are going to say I have low blood pressure but I am 99.99% sure I don't... My mom said it happened to her when she was younger and she used to p out though and it was really severe. She didn't have low blood pressure either... I think it could lead to something more serious because now my mom gets very sore and is sick a lot but no one knows why... Could this be a hereditary issue I should worry about? Will I grow out of it? And I would also like to know how to prevent it. I am almost 14 (will be 14 in one month) and I am average weight. I am healthy but I have asthma/allergies sometimes the asthma is allergy induced sometimes exercise induced. That might help but I don't think it has anything to do with vertigo, hypertension or whatever, or low blood pressure... Should I ask my doctor if this is normal? PLEASE HELP!!!!!