What Do Black Particles In The Stool Indicate?

my daughter has black thread looking object in her mucus, It almost looks like a parasite, but it doesn t move. She first notice small black dots in her mucus, she told our family doctor, but the doctor thought is dust . She doesn t smoke or do drugs. She is having diarrhea, and notice mucus in her bowl movement. Her stomach area is sore to touch, maybe from the diarrhea. She is now breaking out with small red bumps on her stomach that looks like bug bits. Nothing is coming out of the bumps.