Hello and thank you for your post on e health forum.
Blood, mucus in the stool and severe crampy abdominal pain, associated with nausea, are some symptoms that indicate conditions like ulcerative colitis , Crohns disease, Dysentery, hemorrhoids, Ano-rectal tears, etc.
You might consult a gastroenterologist who might get tests including stool analysis, Barium studies, CT scans and a lower GI endoscopy to know the exact cause of your symptoms and initiate proper interventions.
I hope this helps.