Since there is blood which you can see, it is coming from the lower gut. The possible causes are hemorrhoids, rectal polyps, colon polyps, diverticulosis (outpouchings from the bowel wall), inflammatory bowel disease (IBS, Crohn's, Celiac, ulceative colitis), or dysentery.
In hemorrhoids the blood falls after the stool. In fissures it lines the stools. In all other problems the blood is mixed with stools.
Since it is falling after stool, it is probably hemorrhoids, but it is difficult to confirm on net. Do discuss this with your doctor and get yourself examined. Take care!
Get to the doctor this is nothing to play around with do not wait for this to get even worse I am telling you as somebody who knows! I know because I recently had hemmorhoid surgery although I do not think it did a bit of good!
Hopefully ti will be different with you I hope you feel better soon!