What Causes Migraines, Dizziness And Hot/cold Spells?

for the past week or so i have had migraines and its hard to stay on task when do things, ive been sleeping more but still tired all the time, i feel dizzy when standing up for awhile, and i have cold/hot spells, i feel like im always gonna pass out. im 15 years old about 5'3" weigh about 105 pounds and im usually healthy