My child had a colorectal polyp removal surgery by laser, however about 10 days later now there was a droplet in his stool once. should i be worried about this? he is also facing immense itching in anus area, it seems red and inflamed, why so?

Bright red blood on the surface of stool comes from near the outlet, usually from an internal scratch or fissure. These follow bulky/hard or dry stools. Darkened stool comes from higher up where enzymes have been active. Anal itching at that age can be from many things including food allergies, fungal infections, bacterial infections or just habit. Pinworms are rare at that age.