For all those who are asking about remedies for having a problem with mucus and nasal drip down back of throat. I have found the following helpful but not necessarily a cure. I am not a medical professional. so please check with you doctor first if any of these suggestions will be ok for you to try.
1) Stop consuming dairy products, as these actually create more mucus, especially cow's milk or products containing cow's milk. Replace cow milk with organic Oat milk or Almond milk. You may find adjusting to the taste takes a few days, but keep at it. As regards cheese, (I really like cheese) I still have a very small amount, mainly a thin slice or two on a sandwich or grated on a meal. Cheese made from goat milk is better than cow milk but it is still dairy. 2) An antihistamine tablet, such as Zistra (Cetrazine Hydrochloride) or Levrix can help, but check with your doctor first if it is suitable for you and will not inter-react with other medications you may be on. 3) Use a saline sinus rinse to clear out the sinus passages. I use 'NeilMed Sinus Rinse', which comes with saline sachet packs. These can also be bought separate to the Rinse bottle. Most Pharmacies will have these. Just squirt it up each nostril and sniff it into the sinus passages. Wait a moment (30 seconds or so) and then gently blow your nose to clear out the mucus buildup. You can use this whenever you feel the need to, but it is good too do every night just before going to bed. (Just follow the instructions and make sure the rinse bottle is kept clean and sterile). This will also help with keeping any sinus infection away. It would be advisable to see your doctor to just make sure you don't have a sinus infection though which is also causing the mucus. 4) If you are getting a buildup of mucus or phlym in your throat try gargling with sea-salt (not standard white table salt) . You can also swallow a small amount to get it further down the throat. This helps disolve the mucus/phlym.
5) For those who suffer dizziness from low blood pressure when getting up in the morning or during the night visit, this small amount of sea-salt can help eleviate it. The reason we get dizzy is because when lying down and sleeping, our body's blood pressure goes down naturally and so when we get up it takes a minute or so to readjust and build up again. Thats why we are told to sit on the edge of the bed for a few moments and move your legs and arms about. However, please check with your doctor before doing so if you have any other underlying medical blood pressure problems, whether it is high or low blood pressure. and what medications you are on for it. Hope this will be of some help.

I also have a runny nose 75percent of the time,and a cough with mucus,my hospice nurse( not dying,new program to keep you healthy and out of hospital) says it's part of PD. Have been told Botox injections in nose helps,thinking of having it done! Ins supposed to pay for!!! That's great if it works!!!

Also chewing sugarless gum helps.

Thank you so much!