I am not a doctor or medical professional so I can only offer an uneducated guess. It seems to me that you might be suffering from post-nasal drip. From what I've read as a amateur, it seems that post-nasal drip can have a multitude of causes: cold temperature, dry air, spicy food, certain nasal sprays, objects stuck in the nose. Allergic rhinitis is a medical condition that can cause it. Flu can be a cause. Also deviated nasal septum. These are common causes. A very rare cause of post-nasal drip is cystic fibrosis.
There are prescription and over-the-counter medications for post-nasal drip.
But please do not rely on what I have written. I am NOT a medical professional. A visit to a medical professional would be my best advice for you so you are not at the mercy of the guesses of amateurs like me.
I suffer sometimes from short-acting and long-acting post-nasal drip. I use over-the-counter expectorants and antihistamines for relief.
So sorry I could not be helpful to you!