Just passed a stool. it was hard and very lumpy, and was difficult to pass. also had a little bit of blood on the tp afterwards, what could cause it?

Most commonly: Either a hemorrhoid(dilated vein) or an anal fissure(a break in the surface tissue), but it's hard to say without examining you further. You should try to optimize your bowel health to avoid hard stools that require you to strain. Stay hydrated, eat fiber, consider using an over-the-counter stool softener in the short run like colace, (docusate sodium) consider sitz baths. You should review this with your doc.