Oops, wasn't quite done. I also wanted to let you know that the fact you're having pain on both sides, instead of one side of your body, might actually be a GOOD sign (even though it sure must not feel like it to you). Unilateral (one-sided) pain is generally more worrisome because it could signify a diseased organ or a blocked area of the intestine, etc. Sometimes bilateral pain can indicate disease activity as well, but I don't think that is as likely a scenario. Also the fact that you've had some imaging tests done and they are clear - that should be comforting.
Granted, none of this helps the fact that you're in pain. I seriously understand where you're coming from; it sucks when no one can give you an answer to that kind of pain (I've been there too). Can you describe the pain? Is it burning, crampy, sharp, dagger-like, constant or intermittent, and where is it located exactly? On a scale of 1-10, 10 being the worst pain you've ever felt in your life, how would you rate it?
The bright red bleeding probably means you have some irritation on your bum from your bathroom trips. I also had red blood and also fecal occult blood with "no explanation" (that's what the docs said; the GI said my hemorrhoids were of the non-bleeding type) and I attribute it now to the fact that my bum just gets irritated when I have diarrhea or even just "normal poo." This is what I suggest for that: every time you have a BM, use wipes soaked in witch hazel (Tucks pads) to clean up with instead of regular toilet paper. It might sting initially, but is pretty soothing on the behind.
As far as your pain...you've seen a gynecologist, right? You might be in the beginning stages of endometriosis or another gynecological issue that wouldn't necessarily pop right up on a CT scan. Have you had a pelvic ultrasound done?