Many of the posts on this thread sound like vocal cord dysfunction/paradoxical vocal cord motion. I'm diagnosed with that and have the exact same experience with not being able to get a breath through and repeated yawning and deep breaths that a lot of people here are describing. I saw one post mention that VCD is caused by trauma to the throat that mechanically damages the vocal cords in some way--I don't think that is really the case, at least not for everyone. I've never heard that explanation before, and I recall any neck trauma that could have caused my own VCD. So I wouldn't rule it out based on that.