These symptoms sound pretty severe! You should go see your primary care doctor
right away, as they should be able to help you figure out what is going on and recommend a treatment to get you feeling better as soon as possible!
Although you are right that outdoor allergies from pollen are not common during the winter months, it is still possible to be suffering from 'indoor allergies'. These include allergies to things like mold, mites, cockroach or mice droppings, and the like. Indoor allergy symptoms include nasal congestion, cough, and sneezing. Since the allergens are often concentrated in the bedroom, the symptoms are often worse at night and first thing in the morning. Similarly, sinus congestion is a problem that can be chronic and can lead to symptoms similar to those of indoor allergies.
Fortunately, both sinus congestion and indoor allergies are problems that have a solution. If your primary care doctor confirms the diagnosis, they can recommend one of several medications, including anti histamines or nasal steroid sprays. In some cases, irrigation of the nose with a saline solution can also be very helpful.
Go see your doctor right away, and I hope that you are feeling better very soon!