First thing's first, find a new doctor. -__- Clearly they have no intention of helping you. I can't believe they'd say what they did; shame on them. >=P
Secondly, as I have chronic fissures and tearing (the anus won't stretch under a lot of inflammation, it just tears) my doctor prescribed Anucort hyrdocortisone rectal suppositories. If not for them, I'd still be in almost as bad a pain as you if not the same. I was using topical lidocane (2% before the BM and 5% after) to try and cope but that just wasn't enough. It was still leaving me with anxiety and like you, I didn't want to go and would postpone it till I couldn't standing it or was physically sick. Yeah...lots of screaming and crying...and praying... @_@
I can't remember if mine was for 8 months but I know for about 6 months it was really bad right before the suppositories were administered. Now that I think about it, it was gradually increasing over a year's time. While I never lost blood like you did in the amounts, I did bleed only thanks to the tearing. I now too have hemorrhoids that will bleed with the more uncomfortable BM's. It's always sore, but the Anucort does keep things from tearing so much if at all and has healed with nightly use, the fissures. Though I still have the maligned rectal tissue poking out like a bird beak from my butt as that's just kinda how it healed. =/
I'm so sorry you're havin' these issues. I feel your pain and understand. (((((hugs))))) But definitely find a doctor that will actually seek to treat you and maybe try the suppositories. Relief is a possibility, it's just a matter of finding what works. Oh, and as you're 21, I would think you could also have the option of Humira as I was on that for a while and it did really help. Had to stop though thanks to my body attacking it. -__- Apparently it doesn't do synthetic.