I am having a metallic taste in my mouth and a worsening"hacking/phlegm" cough. in case its relevant, i am also taking zoloft (sertraline) and claritin for allergies. what should i do?

Probably phelgm: Mucous secretion due to that produced in the upper sinus passages and upper airway as well at that produced in the lower respiratory tree can drain into the back of the mouth and when tasted, can have a metallic taste pending the type of infection, some blood and if mixed with medications, food and other ingestants, give the metallic taste. If this doesn't clear with "wellness" get checked out.

May not be allergy: One possibility is atypical or "silent" reflux. I know this may sound strange but if stomach juice comes up it can reach the voice box region leading to significant coughing. If even a little stomach juice reaches the mouth it can be very bitter or "metallic." stop drinking acids. No sodas, coffee, tea. Stay away from tomatoes and sauce. Don't eat or drink for 3 hours before bed. See your md.

Post nasal drip: Allergies are bad right now with all of the leaves falling. As another poster said, you are probably getting excess mucous running down the back of your throat. Try using a neti pot from the drug store. You also could just be getting sick. If the mucous turns green or you start to get headaches think possible sinus infection and see a doc. Otherwise see how you do if your allergies improve.

Pertussis?: There is a recent pertussis outbreak going on, with cough that just does not go away. Zithromax can be used. Could also be a sinus infection.