My situation is a bit different as I have no chest tightness nor pain but I do have a huge amount of thick, sticky, mucous. It is so hard to bring up that I've aggravated a bulged disk in my neck. Even though our problems are different but are similar in terms of how long we had vaped before our problem suddenly showed up and can't be pinned down to a particular base ratio nor nic level, I want to pass on a something I've learned doing research. The Mayo Clinic says that when stopping smoking the bronchial tubes will narrow, it can take 6-to-8 months for this to happen. They say that to someone who has smoked a long time it may seem to them that their lungs are more sensitive because of this narrowing. Your tightness is on your left side, my mucous production is on the right side high up, even with the collar bone and slightly below and going across to the bottom of my neck. Is that where your tightness is but on the left? Or is it deep down in your lung? Do you cough inhaling now but haven't had a problem inhaling before? Does smoking a cigarette actually seem to help? It does me... it actually seems to help bring up the mucous build up that causes wheezing at times. Smoke is the only thing I can inhale without a problem. The minute vapor hits my throat and that upper right side of my chest, violent couching begins. Yesterday I tried not inhaling vapor but must have gotten some just breathing because this morning awoke with the same thick mucous that took an hour to bring up (not from lungs but high up and under throat and to the right upper chest.) When your chest is tight, have you tried coughing to see if you're congested then? I ask this because I did not know how congested I was until the violent coughing started from vapor hitting my throat. I had no idea all that stuff was there as it didn't move around and cause a tickle. Sorry... have to go but will come back to see your reply. Hope I've helped a bit.
Edit: sorry this is so long... I was in a hurry expecting company and just did some rapid typing. Anyway what I was trying to get at was bronchial spasms from the tubes being narrower now. Just today I've learned that I can inhale 33% VG with light menthol and no other flavoring and, so far, have only tried 6mg but tomorrow will up that to 12 mg and see what happens... but so far I'm tolerating it as far as the back of the throat hit cough goes and am hoping it will actually help with the bronchial situation. I'm so sorry this is happening to you. You can see, I really do know how it feels... so disappointing.
after knowing how bad smoking really was now to think that i'm back to it makes me feel terrible. If only there were some answers to why this happens would really help. I'm sure more findings will come in the near future and maybe than i will be coming back to vaping again if i'm still a smoker ...There will soon be a garage sale on the classified sometime soon 
