You need to have the source of bleeding identified as that isn't normal. The obvious method will be a colonoscopy as ggreg mentioned. It's the gold standard for this sort of thing.
Obviously you need to see a doc right away. There are medicines like hyoscyamine that relax bowel spasms and stop diarrhea-type symptoms. Most likely you have a bacteria in your gut that is causing all these crampy symptoms, which a doc can give you antibiotics for it. But there is also a chance with the blood symptom that you may have a growth that is obstructing passage of waste, and this must be ruled out! Keep in mind while they'll want to do a colonoscopy for that, those are for the large bowel... to find any growth in the small intestine, it takes an ultrasound and/or scan to do that.
By the way, cramp-like symptoms can come from gas, very painful, so do take an Original Alka Seltzer to hopefully calm that down until you get into the doc. Also, drink some extra water, and get some probiotics in you via stuff like Activia yogurt or Acidophilus milk from the grocery store for a while.