it could be blood released from your liver. The liver filters out dead and dying blood cells from the circulatory system, it's one of its main jobs. These tend to turn dark brown during regular digestve process, but enemas get them out faster so they keep the red color. But just in case this was fresh blood, keep to a liquid diet for a day or two and rest/withdraw from most cleansing activities for 3 days. You can drink aloe vera juice to speed healing and make your next enema one with liquid chlorophyll instead of ACV, this is very healing and soothing to the bowels.