I Have Been Constipated For About 4 Days. Yesterday ,

I have been constipated for about 4 days. Yesterday , I began to bleed from the rectum every time I had to urinate. I looked and there was some protrusion of anus. My lower GI is very crampy and bloated, but my upper GI is in a lot of pain, burning, nausea, and vomiting of dark green bile ( I don't have my gallbladder; it was removed Nov.2001)
Today the bleeding is reduced but pain, pressure, bloating, nausea. Should I wait til I find a GI doctor or consider the ER?