Mornin confused,
I was on birth control for 3 years myself. When i stopped taking them, my periods became very eratic. The cramps were unbearable at times and my breasts would swell and become very sore. I also would get a back full of pimples, something that i never had even when i was a teenager. For some, coming off the pill after an extended period of time can throw your cycle off track, it may never come back to normal. I never knew when i was fertile, i never knew when i was ovulating, i knew nothing. I was trying to have a baby, so it was "hit and miss" for me. I had several false alarms but eventually got lucky.
I think this your period trying to come on, but if it doesn't resemble a normal period with a normal duration, i would take a test.