Falling without reason as a teenager?

It started when I was 14, then it stopped for a while and I thought that it was over. Then it started back up recently at fifteen. (My current age) It mostly happens in the morning. I ll be standing up then I lose feeling in my legs then I m on the ground. I never remember when I am in the process of falling, I only know that I was standing then that I wasn t. I don t know if it s fainting, or if it s something else. I know that I m healthy, and I m not epileptic. I do take medication: Vyvanse, Clonidine (a very low dosage for insomnia) Seroquel XR, and Prilosec. I think I spelled them right, sorry if I didn t.