Bleeding and irregular tests to be followed by Colposcopy

Hi, I'm currently on the Depo-Provera shot and the past two years at least I have had abnormal pap smears.  My doctor was worried and scheduled a Colposcopy for me.  I've been bleeding for the past 3-4 weeks and have had to reschedule because of it.  The bleeding has been light but dark, more black than brown for 2-3 weeks until this week which started with pink and is now alternating red and dark.  I'm worried there is something seriously wrong.  I have abdominal pain and what seems to be a bladder or urinary tract infection.  I also had nausea for a day.  I'm starting to think I should not be on the Depo shot.  The only things that came up when I searched was: Miscarriage, HPV, Cervical Cancer, Ectopic Pregnancy, or an STD.  I've been going crazy the past month worrying and with the rescheduling now I'm even more concerned.  Please help