Why Am I Having Period Pain Like Cramps And Dark Brown Discharge?

hi. im 22 im 5ft 2 and ive recently come off the pill mercilon after 9 years to try for a baby, yet the last two days ive been getting period pain like cramps and dark brown discharge is this anything to worry about .? and also how long will it take for my body to come back to normal after being on the pill for so long ??