Blood in stool for three days now....with the most recent bowel, i have become extremely nauseous and light headed. should i visit the emergency room?

Yes: Hard to tell how much bleeding there is and as such the amount lost. Normally from hemorrhoidal bleeding one doesn't become symptomatic. the light headed ness suggests the possibility that there might be a colonic lesion and that bleeding may have occur longer than suspected. As such you would need a blood count to know if you are volume depleted and require transfusion and colonoscopy.