Is this cervical cancer?

Hi
I had a healthy pregnancy 6 years back and all my last pap smears so far came back normal and at least my OB/GYN never said any concern about my health. In Jan 2012 I went to OB/GYN when I experienced bad itching and some kind of spotting and he assured everything is fine. I have been bleeding little heavy since I gave birth but never been on any pill. Since my husband is having some health issue so for last 3 years we are not having any intercourse. So in May when I had my regular period I was having 3 days cramps prior to my period  and then period was heavy but got over within 4 days. Now within 10 days after my period I started bleeding again and went to see my OB/GYN who asked me take pills to stop my bleeding.Today is the 3 rd day I started taking pills and bleeding stopped but when I wipe I see some black discharge or pinking discharge. I also have lower back pain and my GP says this is due to my tender back. Anyway, last one year I had lots of blood test /all types of ultra sound/pap smear and nothing was detected. So I am really frustrated that my general health is getting worse and worse and nobody could find anything. Finally now I am stuck with bleeding and within 6 months since I saw my OB/GYN how could I develop any disease? I am really worried. IS it cervical cancer? I always have bad yeast infection. However never diagnosed with HPV.