Sorry your mom isn't coming around yet, Anna. An ENT is definitely where you should be headed. In the meantime, more frequent nasal rinsing with saline (and distilled water) is a very good move in general, especially in the winter. Last year my allergist addressed my constant throat clearing from post nasal-drip by having me try AstePro nasal spray. You can buy it over the counter. It's an antihistamine that you can use in addition to any tablets you might be taking such as Claratin or Zyrtec, and it is known for helping with post nasal drip. I can't say it helped me a lot, tbh, but if that's one of its best known effects, you may as well try it. It's about $15-20. Also, a doctor friend with bad allergies recommends Mucinex as well, although it will make you want to cough up the stuff. Regular gargling with warm salt water will help with bad tastes in your mouth or buildup of bacteria in the throat/tonsils that can cause nasty bad breath. Big hug from a grandma!