You probably have seasonal allergies. In the winter, your house tends to be closed off and less vented. If you don't clean, dust and vacuum your house on a regular basis, you have a build up of dust and dirt and that can make allergies worse. Sometimes all you are allergic to is the dust. Also, in the winter, the air tends to be dry. A good way to reverse that is to have a humidifier in your room. Cleaning won't hurt either. Wash your bed sheets every other week or at least once a month if you are too busy. If your symptoms seem to be worse in your room, then that should be where you start cleaning.