Hiya!
I get something like this too sometimes. But easily addressed:
I. You quit smoking sometime in the past 12 months. Your entire respiratory tract is beginning to heal and produce as much mucus as a healthy non-smoker, which is going to loosen up all kinds of nasty stuff from deep in your sinuses to the bottom of your lungs, not just tar but all kinds of stuff you inhale daily that a nonsmoker would have cleared out much sooner. This is one of the things that causes the infamous "quitter's flu." Everyone heals and clears at different rates, factoring in length of time and daily quantity at which cigarettes were previously consumed.
II. VG ratio too high. Easily fixable.
III. You are not drinking enough water. Even mild dehydration affects the thickness of your mucus; thicker mucus tends to hang around longer and pile up more than thin mucus, meaning you're going to end up hacking up some lumps every so often because it isn't clearning as quickly. Vaping nicotine dehydrates you in more ways than one, most of them having nothing to do with how water is "binding" to what kind of vapor and whatever. Nicotine itself increases loss of certain electrolytes and can deplete certain vitamins. This has nothing to do with smoking but the actual stimulating nicotine itself.
IV. You are vaping too much, full stop. Irrespective of VG/PG ratio. Though vaping can dehydrate you, the vapor itself can also act like a humidifier or hanging out in shower steam, loosening stuff up in your tracts; it is, after all, vapor. (I sing for fun, not pay, and vaping has the same smoothing effect on my voice as steam, especially vs analog)
V. You are vaping something that is irritating your tissues and triggering mucus production. This could be anything from a sensitivity to an ingredient, could be anything from the base, to flavors or additives like sweeteners, citric or malic acid (often used to either preserve flavors or enhance tartness or sourness of flavors, or both), or other flavor enhancers like acetyl pyrazine (enhances nutty flavors), vanillin, vape wizard, etc. It could also be caused by improper cleaning/reusing of atomizers with various chemicals, vaping alcohol
VI. Here's the big one that nearly everyone in vaping forums miss, and is the very reason I created this account today (to post in some threads where people are asking about why they feel chest tightness, I have never seen this mentioned in any "chest tightness" threads AND IT SHOULD BE mentioned with all the other potential causes of tight feelings in chest and shortness of breath): NICOTINE ITSELF, AS A NICOTINIC AGONIST, IS CHOLINERGIC. It binds to nicotinic acetylcholine receptors, mimicking acetylcholine. This in itself is neither a bad nor good thing, acetylcholine is a neurotransmitter like dopamine, serotonin, histamine, etc; it's all a matter of "how much" and keeping things balanced. Acetylcholine is one of the reasons mild-moderate doses of nicotine temporarily enhance memory and certain cognitive functions. Because of this, nicotine is sometimes used in nootropic circles, though not widely recommended due to less harmful methods of cognitive enhancement. It's also one of the reasons heavy smokers (AND heavy vapers) are likelier to suffer from depression and/or anxiety, insomnia, and general twitchiness in varying degrees. And it's why Wellbutrin (bupropion) has had some success as a smoking cessation aid: it's a nicotinic antagonist, blocking nicotinic acetylcholine receptors, decreasing the pleasure one gets from nicotine.
More pertinent to this kind of discussion, however, is the fact that acetylcholine stimulates mucus production (this is why all prescription and OTC drugs that are anticholinergic have thirst/dry mouth-type side effects). Another way nicotine indirectly stimulates mucus production is through the glutamate-histamine relationship; nicotine increases glutamate release, which in turn stimulates histamine response. This also contributes to both positive and negative effects of nicotine on the brain/body. This will naturally effect different people in different ways.
