A deviated septum is an extremely common condition that you may not even know you have. Your nasal septum is a wall of bone and cartilage that gives shape and support to your nose while dividing your nasal cavity in half. In some cases, however, it’s off center or crooked. This can make breathing difficult and cause congestion to build up, particularly in just one nostril. Your nose may feel stuffy, even when you don’t have a cold. In more severe cases, it can make the nose appear crooked.