First, milk has been proven in study after study to have no effect whatsoever on mucus production. So, drink as much milk as you want. Sugary drinks don't cause mucus or half of America would be walking around with "snot hanging to the ground". Mint tea won't fix an allergy or infection, and elderberry supplements are voodoo. There isn't a properly conducted study proving any of these to have effect.
SO, NOW FOR THE INTELLIGENT ANSWER.... Mucus over-production is caused by an irritation such as allergy, virus, or bacteria. It's your body's attempt to flush out the offender. In your case, the mucus is clear, seems to come and go, and doesn't come with other symptoms suggestive of infection (fever, malaise, pain, etc).
Most likely, you have simple allergies to airborne allergens. You can try taking a newer generation antihistamine such as Allegra or Zyrtec every day for 3 weeks straight and see if it improves. If it does, you have a good idea of what's going on. Then, you have to figure out what you are allergic to in your environment. If you can't find something obvious such as a cat, dust, a tree near your window etc, then you should get allergy tested (it could be airborne molds/pollens or 100 other things) and have an immunologist take a look in your nose. Sometimes just the color of the turbinates in the nostrils inside tells a lot...raging red=infection, purple/blue=allergy. Then, he can prescribe one of the newer nasal sprays such as astelyn sodium or Flonase, etc. Good luck.
Stop drinking milk. Take elderberry supplements. Drink mint tea or green tea with mint. Drink more water and stop sugary drinks.
thanks a lot...very informative...can i try oat milk?
i believe that my pillow has dust mites...i am airing the pillow now to see what the results will be...will keep you posted...