These are pieces of flatworms (maybe flukes). I am not sure but very likely. If you pour hot water on it and it does not dissolve, it is a worm. Bloody stools can be a sign of many things. The red colour of these pieces could point to a blood sucking worm, but you could have hoowkworms or other pathogens. The sesame seeds can be roundworms (i have had those for months, many many, they were cysts) and in a more rare case, Tapeworm (those look more like long grain rice).