Can drinking bad milk cause the color of stool to change?

Lots of things can: The amount, color, frequency of stool varies with foods, speed of emptying of the GI tract, medications &supplements ingested, gut flora (unique for each individual), additives (like blood), subtractions (like absent bile), infection, inflammation, &other factors. If stool pattern has changed, is unusual for you, &the change persists, or is accompanied by other symptoms, see your doctor please.