I Didn't Have My Period For 5 Months Then I

I didn't have my period for 5 months then i get my period and it was extremely irregular, lighter than i have ever had a period and lasted longer then usual, My period stopped for about 11 days and started again, its extremely painful and my stomach burns. a few days before it started i got really sick and threw up for 12 hours. I am a 21 year old female