What does it mean if i'm constipated and the poop is small but there's a lot of blood?

Need to see Dr.: Bleeding rectally is never normal, so you need to see a dr., preferrably a GI specialist, and get an evaluation urgently if there is a lot of blood. Good luck.

Fissure/Hemorrhoids: Common things being common, this is likely fissure or hemorrhoids. However, this needs to be examined by a physician to ensure it is not one of the less likely, yet entirely plausible causes.