It sounds like you're having bile. Have you talked to your doctor about your new symptom? I don't know of any home remedies to help with bile. I had it so bad that it prohibited me from eating and I had no choice but to take a prescription, but it did go away, and I haven't had it since.
From my experience, if you can keep your heartburn at bay and not troubling you, you will not have any bile (pungent liquid in your throat). I've never had bile without having heartburn.
As for trouble breathing, that could be a result of your heartburn. I know when I have heartburn, sometimes my chest feels tight and I have to take several deep breaths, because it feels like I'm not getting enough oxygen. Are you on any medicine for your heartburn? Maybe you should try a different medicine, it sounds as if it isn't working as well as it should.
I hope you feel better soon, please let us know how you're doing! :)
You can't say
I didn't give it
I won't wait
On my way
This time around