From what I can gather from the google machine, your Ecto BDC is a clone/similar design of the Aspire BDC.
Looking at various Aspire BDC "dry burning" or "cleaning" responses on the internet, it appears many people have trouble dry burning or cleaning this design and many of those threads recommend just using fresh replacement coils. It sounds like it's difficult to get everything dried out enough after rinsing and it's apparently difficult to get enough water to the coils to properly rinse them. There are a bunch of posts on various websites with your similar description of not being able to get the coil to glow, which either means the design is holding a lot of moisture that takes forever to burn off or you have a defective coil.
I don't have an Aspire BDC or an Ecto, but my concern with your severe reaction is, in addition to not being able to get it totally clean, you may have also melted an insulator with a hot leg trying to push power through a gunked up or burned out coil and inhaled it. That's just speculation on my part. I don't know what kind of insulator this design uses, but I can tell you that a burning an insulator on a Protank and inhaling it is a lot like you describe. A normal dry hit or hit from a dirty coil will taste bad but shouldn't make you feel like you're going to die.
Back when I was dry burning silica wicked devices (I cut my teeth on Vivi Nova's and CE4's) I made it a habit to never actually inhale (just mouth hit and blow it out) until I was confident I was getting a clean juice vapor and not steam or burned gunk coming off the coil. It was always hit or miss on whether an attempt to clean a used coil was going to be successful or not, but I always insisted on getting it to the point where I had a clean, glowing coil before I considered filling it back up and using it again.
Read up on the Aspire BDC and see if it looks like the Ecto you're using. You might find some useful tips.
Here's a Ripp Tripper video describing crossed leads, shorts, and only a 40% success rate with new Aspire BDC coil heads due to shoddy manufacturing. It wouldn't surprise me if the Ecto has the same issues.
https://www.youtube.com/watch?v=pwgkYUgZXHI