Feeling Lethargic,bad Headache,lower Back Pain & Pain In Pelvic Area

I have been on the depo provera injection for around 16 years and have never experienced any bleeding;maybe a slight bit of spotting! At the moment I am bleeding enough to be using pads and am probably going to change to tampons soon! I have been very lethargic and have had really bad headaches/ lower back ache and sore tired muscles all over and legs and pelvis have been very achy,spasmy and restless and just exhauseted and out of breath really quickly and easily without doing anything strenuous at all!