My Crohn's is mostly in the rectal area, so I get lots of bleeding when I am flaring, and a little at other times. The trouble with blood work etc. is that if the inflammation is only in the last couple of inches of your digestive system then your blood work may look normal. Also, the prednisone may take a while to kick in. It took me a stay in the hospital on IV steroids to stop the bleeding. The Asacol (which I think is like the Salofalk that I take) is not really that effective for treating a flare. It is good to keep you in remission, and you should definitely keep taking it (IMHO).
It sounds to me (not being a doctor of course) like you need to do something more than you are doing. I wouldn't necessarily start with prednisone orally. If you can try rectal foam topical steroids, or 5 ASA enemas or suppositories it may take care of the bleeding, and would not have as heavy side effects. I would definitely return to your doctor/GI and ask for more action. When I was in the hospital the GI on call was most clear that the bleeding needed to stop. Your GI can do a sigmoidoscopy with no prep etc. to see if there is still inflammation in the colon/rectum.
45 years old. Diagnosed with moderate to severe Crohn's in April 2005. Hiatus hernia diagnosed in 2008. Had Crohn's under control until March last year when I had a major flare up and ended up in hospital. Diagnosis is now CD and IBS. Getting it under control again.
Currently taking: Salofalk 2000 mg, Nexium, Calcium and Vitamin D, Matamucil, Yogurt for probiotics, Salofalk suppositories as needed.