I have been at it for a while, and it takes time. Try not to misinterpret the symptoms, your body is going through a lot. See a Dr. and discuss the symptoms with him/her, you cannot replace medical training. I found out a few months in that I am PG intolerant. I would get "heavy lungs" and hot flashes with non specific itchyness on my torso and arms. Honestly I don't think I noticed it and wrote it off as part of withdrawls, and until I had leveled out.
All of us are different. I would suggest as many do to get some 0 nic pure unflavored pg, and same in vg. Vape both and pay attention to yourself, if the breathing clears on one and not the other, you can assume with relative safety that you are intolerant to one of them, if not and the symptom persists PLEASE go see a doctor, it could be a symptom of quitting, but you are far better safe than sorry. Vaping is a learning experience and there are no real direct answers that anyone can give you with 100% certainty.
That being said I am not a doctor, I have just been doing this and lurking the health and safety board for some time.