Hi. I Have A Doctors Appointment Friday To Check Liver/kidney

Hi. I have a doctors appointment Friday to check liver/kidney values, mainly because for the past 5 years I have had a 6 pack of beer a night. Give or take. For the past week I have abstained from alcohol but today noticed frank red blood in my stool. Other than a little light headedness from the shock of the sight, I feel fine. Just a little crampness in my abdomen after passing the stool but otherwise no other symptoms. Would waiting until Friday be ok while I just monitor my stools or should I seek out an ER sooner? Thanks- Jay