A lot of mucus in stool for months now, random cramping. now diarrhea for past 4 days, random cramping, and now blood and mucus. cause for concern?

Recommend: I do recommend that you see your MD for an evaluation. It could be infectious or inflammatory and good to have an evaluation.

Yes it's a concern: It sounds like you have an inflammatory process in your intestinal tract. There are numerous potential causes, both infectious and non-infectious ones. Some are serious, such as diverticulitis, inflammatory bowel disease (Crohn's disease, ulcerative colitis), and more. Get evaluated promptly; your PCP probably will refer you to a gastroenterologist -- or contact one directly.