Can fatigue and mucus and blood in stool be related to anything thats not cancerous or life threatening?

Yes (Colitis) Anything that causes inflammation of the inner lining of the large intestine can cause these symptoms, including inflammatory bowel disease (crohn's disease, ulcerative colitis), infections, etc. Many of these processes do not get better on their own: please see a doctor as soon as possible.
Consider IBD. Inflammatory bowel disease (crohns, ulcerative colitis) typically present with abdominal pain, diarrhea, and blood / mucus in your stool. See a gastroenterologist for evaluation of your symptoms.
Yes. Yes other conditions can present this way. Please consult a doctor for diagnosis.