Two year old son has very dark, runny stools that have left him with a bad rash on his bottom. could this be a result of an infection?

Some basics: Dark runny stools are often triggered initially by many gut viruses. Over time the infectious process irritates the gut enough to cause poor absorption/nutrition & a "starvation diarrhea" occurs. The material can be very acidic & burn anal skin. It also contains germs & yeast that can trigger rashes.Barrier ointments & anti fungal creams help. Applesauce & fresh banana slows the poop.