Frequent Headaches Which Changes Position. Pain In Veins Of Hands And Finger, Nauseatic Feeling. Had Laser Eye Surgery. What Could Be The Cause?

Hello I am a 19 year old female and for about 3 months now I had got headaches , not very strong ones but stil. It usually changes sometimes it is on left sometimes on the right hemisphere of the brain. And also behind my eyes. I also have sometimes pain in my veins in my hand and my fingers. I also feel sometimes nauseous, mostly when I lay down, as if I couldnt eat anything, however I eat normal. I dont know what may be the cause, I could mention that I had laser eye surgery last year, or maybe because of my spine, because as you see I am still at school and I sit a lot for hours in one place. Hope you can find an answer to my problem. Thank you very much. :)