Why Am I Having Period For 3 Months After Having The Implant?

hi im 23 years old, 5ft 2 and 9st 7lbs. i have post natal depression and im on the implant., does any form of medication stop the effects? another question i would like to ask is....iv had the implant once before and no effects ect it was great, then decided to plan a baby so came off it. i had it put back in last year and most days my arm aches and is irraratated. iv been on my period for nearly 3 months now (its been a year since having it in) and im suffering really bad headaches... any suggestions or help would be appreciated as the receptionist at my doctors arent pleasent and im struggling to get an appointment.