That is an excellent question and one that is best answered by your primary care doctor
or another medical care provider who can examine you and obtain a complete history to assess what may be the cause of this mucous in your stool. Based upon the limited history you have provided, it is difficult to know the underlying cause and so it is imperative that you are evaluated by a medical professional who will be able to perform diagnostic tests if he or she believes are relevant and then decide upon the cause of this mucous in your stool. Some potential causes of this could be infectious, as there are certain GI infections that can cause changes to your stool and its appearance. It could also be related to your diet, depending on what you are eating, there may be something that looks concerning in your stool and it may be as easy as stopping consuming this item for your stool to return to normal. You could also have some issues related to your GI tract and the way that your body handles certain nutrients and food items and that may be causing you to have these symptoms. Only your doctor can find out the cause of this abnormal stool finding.