My period doesnt come very month.. what should i do?

im 17 years old and i gotten my period when i was 14 (kinda late) around 15 it started skipping and i found out i had a cyst. i took birth control as a hormonal medicene and it went away. now im 17 and my period skips and when it doesnt come i break out on my face, i sweat alot and i get the worse pain EVER in my lower abdominal, rectum and crotch. i also get burning when i pee and i cant seem to sit down or close my legs from all the pain and discomfort. i went to many docters in america and outside the country. nothing works.. what is wrong with me? i took a xray of my stomach and theres no cyst and theres nothing wrong with my hormones. im very confused and the pain is makeing me stress and its makeing it harder for me to focus on my school work. anyone please please help