Please...help!!

Hi -- I've been living in pain for the past 8 months. Nobody can tell me what is going on. I've seen 3 colorectal specialists, had sigmoidoscopy, anoscopies, MRI of my pelvis with contrast -- nothing. The blood test showed mild anemia --  I rarely eat meat...  All started in February of this year -- I passes a bit of bright red blood with my stool. No blood since. Yet, I have horrible pressure pains (closer to tailbone feeling, yet inside of my intestine) that do not go away. Sometimes it is painful to walk, sit... Longer I sit, worse it becomes. I feel very strange inside of my rectum. My period was off for that time, too. I did not have one for 3 months, then for 2 months, now for 45 days. It is very strange for my body...