Can Implanon Contraceptive Implant Cause Cramps?

Hi doctor. I had the implanon contraceptive implant put in in november 2009. For the last year, i've been getting severe stomach cramps, mainly at night that can last up to 30 minutes (i usually take pain-killers as soon as it starts) and I can get them every night for 2weeks at a time. Is this a normal side-effect of the implanon after having it for over a year?Is there anything I can do to stop the severe cramps as they are extremely painful.