Extremely lightheaded

So I wake up this morning and slightly turn and everything starts spinning. I wait a few seconds and try to get up and fall right back down and well all of this is repeated for awhile until I finally get up. I go downstairs, have breakfast but I struggled to walk and had to hold onto the stair rails and the walls the whole time. I'm 15 and i am really scared right now. I've had plenty to drink and eat. I haven't been out in a few days cause I've been trying to get ahead for school and I can't think of anyt reason for me to be feeling like this. I've dealt with lightheadedness before but only when I'm standing (I'm feeling it right now and I'm laying down). Anyone got any guesses?