@likevaping -
I really hesitate to speculate - I am not qualified to do that. So please take the following with that very large caveat:
Costochondritis can result from physical strain. I notice that you are physically active. Perhaps without realizing it you strained the cartilage or a muscle or a ligament in your chest? If so then when inhaling you could be expanding or moving your chest in a way that puts pressure on or causes the strained cartilage to move. Or you inhale enough to make yourself cough (the THC in herb naturally causes a cough reflex), which makes your rib cage expand and contract rapidly. What I'm trying to describe is similar to what happens when you crack a rib or hurt your lower back or even strain a muscle in your rib cage - at rest you might not even feel it, but if you turn or move in a particular way - or take a deep breath or worse yet cough - there can be a very sharp pain. And the reason it might happen with the Q but not the MFLB could be as simple as different posture or different inhalation.
Your doctor checked you for a cardiac problem which indicates that the pain you described to the doctor sounded similar to the pain of angina. There are a number of internal disorders which, like the above muscular strains, can mimic the symptoms of angina, and in fact many people go to the ER mistakenly thinking they are having a heart attack from these; one that is rather common is acid reflux. Inhaling a bag could aggravate a reflux condition, for example, if the reflux has really irritated your esophagus.
Something else that comes to mind is that herb commonly causes tachycardia. If you are coming on to the herb and you already have some anxiety - and from your message it does sound like you have a lot of worry about this - that might result in your chest tightening, and that could be painful - especially if you've already strained your rib cage somehow.
Good to keep in mind that stress aggravates a lot of conditions; e.g., it tightens the muscles making a chest or back strain worse, and with reflux it causes the body to generate more acid, or it can make herb negative side-effects a lot stronger. The mind is very powerful, and anxiety can take on a life of its own.
About the Q, I find it hard to imagine how the unit could be the root of the problem. If you were getting combustion, you would know it for sure. And besides, if that were having an effect you would feel it as irritation in your bronchi or lungs, not as angina-like pain unless you have severe asthma or COPD. Your questions about something bad inside the Q, the warranty, etc. do suggest a lot of anxiety about the unit itself.
So just my
- personally, I would just hold off the Q for a good while and let myself heal.
Good luck.