It seems to me from what you describe, it might be that mucous is gathering at your vocal chords and clogging it up. Because of that, it's keeping you from being able to breathe properly.
There's a condition called VCD--Vocal Chord Dysfunction, that causes the vocal chords to spasm/close, and keeps air from moving through properly. With VCD you learn breathing/relaxation techniques to allow proper breathing.
I don't think that's what you're dealing with, but I mention it to point out that your vocal chords can impede breathing.
Would it be the vocal chords if I can still speak/sing properly? I keep googling about
mucus pooling on the chords, and most people say they become hoarse etc, but I don't. :p
What sucks is that until now I was fighting a bad spell of nausea and bowel issues. Now that they've gone, this is the latest problem. Surely LPR can't just drop symptoms just like that?