I don't really know how to classify my block.

I don't really know how to classify my block. I've had this speech impediment since at least 4th grade, that's the farthest I can remember at least. I'm perfectly fine through most normal interactions, Asking for directions, placing phone calls to pay bills etc. But the problems arise when I'm in a tense situation. Having to expllain my side of an arguement, speaking with law enforcement ( i live next to known crack heads ). Or even talking to my boss about anything I'm unsure about. Here's what happens. I feel like I can't breathe, my throat kind of feels like it's closing up. I start to get super warm and my forehead starts to sweat. I don't really stutter, the words feel like they're getting caught in my throat. I'd totally be willing to answer any/all questions if any of this is confusing. I'm 27 years old and would very much like to overcome this one horrible hurdle. If it helps at all. This impediment doesn't appear when I'm speaking in various character accents or if I'm singing.