For 2 weeks now have had bad nasal congestion, post nasal drip, constant runny nose. very bad congestion & nasal drip won't go away. what to do?

Sinus: I suspect this started like an ordinary cold but at this point you may have a sinus infection. Contact your doctor for a more in-depth evaluation since a number of questions need to be answered. Allergy is unlikely at this time of year if you haven't had it before.

Allergies.: That sounds like allergies. Nasal congestion, runny nose, cough, headache, facial pains and earache can be triggered by fragrances, dust mites (sweeping the floor), grass, trees, pets, environmental molds and such. There are outdoor and indoor allergens. See a doctor soon, here or locally, as there are medications that may help.