Constant pain in my head..really worried..doctor ?

Im only 18 years old i dont know whether i suffer from migraines or sinus' often (terrible pain in my left temple all the way behind my eye and my head,very sensitive to light)? Im just after finishing really important exams i was stressed but its all over now. Ive lost my appetite just before exams and still hasnt come back i want to eat but i cant i feel sick if i do,and now i have a constant pain in the back of my head along with this and it gets even worse whe i bend over is it an infection or does anybody know ? i would love to go to my local GP but he is **** he just hands out any old tablets to get rid of you . i plan on changing my gp but for now i would like to know what is it or whats causing this ?