Hello I Am Currently On The Nexplanon Implant. It Doesn't

Hello I am currently on the nexplanon implant. It doesn't expire until January 2017. I have always had light flow regular monthly periods. But for the last three to four weeks I have been having heavy bleeding non stop with mucus and blood clot blood. There is no odor and once in awhile pain in my left side. Cramping in my left side I am u sure what is wrong. I am sexually active with no other protection than the nexplanon. I have no other symptoms besides left side cramping and heavy bleeding