I use to feel dizzy after and when I am studying, I have migraine, what should I do?

Seek a MD. Get a confirmed diagnosis of it, if in doubt also rule out if it isn't tmd.
Caffeine or more. Causes of dizziness or especially headaches when studying can have several causes. Caffeine use/abuse is very common in students to stay awake. Caffeine is often used to treat migraines, but can also trigger migraines and headaches with heavy usage or withdrawal. Sleep deprivation and anxiety can also produce dizziness often go along with studying. Making sure vision is ok is important too.