I've recently been trying to work out how to describe my difficulty talking about certain topics and trying to find out if this is an autism trait, a common co-occuring condition, or just anxiety. Lacking the right search terms hasn't helped in that regard!

Neither selective mutism nor alexithymia seem to be quite the right terms, although it's definitely connected to topics that carry emotional weight. I can have the whole concept or discussion that I want/need to have worked out in my head, but when the time comes my chest really tightens up and my throat feels restricted* and it's like I have to physically push to get the sentences out.

(*) I know that this is a physical indicator of stress and am very much aware that I am stressed in that situation. However, it's not the way I typically experience stress, though (I usually carry that in my shoulders/back and end up with vice headaches from high-stress situations).

It's similar (but definitely not the same) as when I feel like I am bracing myself for a verbal assault (again, that manifests itself specifically in a lot of tension in back). I don't think I'm expecting to be attacked, but it definitely feels like my system is screaming at me to not talk about whatever it is.

This is also distinctly different to when I can't quite explain something or struggle to describe what I am feeling. In those cases I end up taking a minute to work out how to phrase what I am experiencing or describe the concept I am trying to explain (and I almost always have to break eye contact to do this).

Does anyone else experience this sort of difficulty and how would you describe it?

Edited to add clarification (also in one of the comments):

I can talk about lots of things (not just special interests) including divisive issues such as politics (and sometimes even when I know I’m likely to receive an unpleasant response), but it’s difficult to neatly categorise what types of topics cause this. If I had to guess, it would be topics surrounding my (emotional?) needs that are most likely to trigger this. The current one (and this was a challenge to even type) is the fact that a combination of health+work+life factors is currently making me feel like I’m stuck with no good options to resolve them and hence going to miss out on a lot of things in life that I value.

It’s not necessarily dependent on who the other party/parties in the conversation is/are, either. For example, I have an incredibly non-judgemental and compassionate GP and yet one of these instances occurred when trying to work through my health issues this year. My wife is incredibly understanding and patient as well, so it’s not as though it’s an unsafe environment for the above conversation either.