That happens to me, especially if I drink hard alcohol (so I don't anymore, duh).
If you call your doctor now, he/she might say you should go to the ER, and you might need to be prepared to wait for attention there while you continue to pass blood, be given an IV, and still be passing blood but in the hospital toilet instead of at home. Miserable! That's why I always just stick it out, I hate the ER. I also would fight being admitted to the hospital, too, so that's my bias....
We can't tell you what you should do.
Try to call your doctor's answering service now, then trust your instincts to decide what to do. He/she might also tell you when you'll know it's time to go to the hospital.
49 year old female attorney, diagnosed UC/pancolitis 1985, no surgery but much suffering. Asacol/5ASA 6x400 mg maintenance for 20+ years; use prednisone & Rowasa for flares.
August 2008 sought care of naturopathic doctor. Food sensitivity test showed wheat/gluten, other intolerances; eliminated all wheat/gluten from my diet. Probiotics (Ultimate Flora, 50 billion), trying Curamin.
Flaring, seasonal? or supplements too harsh? Back on prednisone, tried to taper but now back up to 20-30 after several really bad days. Waiting for insurance decison on Humira...soon...