Question about period?

Since few months i had regular cycle menstural like on 12th of every months so somehow this month is very complicated like i felt little sharp cramp not that bad and i saw a very light brown spotting non red bleeding. what that suppose to meant ? i dont take Birth Control pills but im ual active with my boyfriend for 4 years....we dont use protection so my ovulation was on 17 days cycle so right now i saw the calender said 27 days cycle as today i saw my spotting but it wasnt bad cramp at all....i crave sugar really BADDDD never happened before to me.....just little cramp thats all i can feel. It suppose be 31 or 32 days cycle for to start period so why today ? i just hope i dont have menopause im only 22 years old.....so please help me if you know or anything on infos thanks