irregular periods

Hi My name is Brittany Butler im 20 years old i have a 1 year old son he was born on April 4th i got the mirena put in May of 08' i been having my cycle every other month sometimes not for 2 months. Around Feb of 09' i havent been bleeding i would have what most woman get at the beginnig of the cycle the brown stuff dont know what you call it. But i been having that for a period lately. It last for 3-5 days. It did not have a odor i would get a sharpe pain in my abdomen once in a while but not everytime i would have it. If you could help me that would be great.