Just 3 days? These are very common IBS symptoms and in no way warrant a colonoscopy. I could give you the medical name for the feeling of fullness in your rectum but you would google it and come up with something far more sinister. I have it a lot and have IBS..and I've had it a lot longer than 3 days. You have to put a check on your catastrophising when there is no medical need, Mr Lurcher.