recently vegan and dizzy

I have been Vegetarian for 1.5 years because I love and care about animals. I recently became Vegan like a week ago and I have felt dizzy for the past 4 or 5 days. Everytime I get up or even just slightly move my head I feel like I’m going to faint. I started taking an iron pill and a B12 pill every day but it’s not helping. I’m going to the doctor tomorrow and I’m scared that he is going to tell me to eat animal products again. Thats what my parents want (Im 16). I don’t know what I’m doing wrong but I’m sure there are ways I can fix it without straying from a vegan diet. Any ideas!? :confused: