A runny nose for 3 years and constantly clearing your throat (which is a cause from post nasal drip) suggest that you have sinus allergies. You said your sx is year round and this could be your allergic reaction to tree pollens (spring), grass pollens (mid summer) and weeds pollens (late summer) and then mold and mildow in the fall and winter, and of cause there are also dust mites, animals dander that are presents year round. If you are suffering, I suggest that you go to see an allergist. Stuffy nose and post nasal drip can be easily treated by prescription preventative nasal spray and antihistamine. Ask your doctor ( preferrably an allergist specialist, not your pcp) today, there are many treatment option to your problem. Good luck on finding a trusting doctor in your area. Remember, there is plenty of effective tx. You do not need to suffer!