I was on the pill for about a year before I stopped. Once I stopped, my periods stopped too and I had stomach ache for weeks. I went to the doctors to find out what was wrong and they said my body was just readjusting to not getting the hormone any more. I waited a couple of weeks and still no period and stomach pains. I went back to the doctors and nothing. About 2 months later I had my period which lasted about 3 weeks.
Finally everything is sorted, and the doctors still say it was my body readjusting. Definitely frightened me enough not to go back on the pill though!