hi
@anniekim
I think this has to do with mental exertion, which can have the exact same symptom exacerbation as physical exertion. During social interaction our brain is super active: listening, processing, reacting, forming thoughts, speaking, ... Depending on who you talk to and what you talk about, this could also be extra exhausting: talking about a sensitive subject, talking with someone who you don't get along with very well, talking to a friend who you haven't seen for a while and there is SO much to talk about and so many facts to take in...
I love talking to friends, but to be honest it leaves me completely exhausted. So I started thinking about how I could make it better. Over the years I have tried to develop ways of talking that make me less prone to PEM afterwards. I don't know what your situation is, but I was thinking maybe you could try to remember some of the latest conversations you've had:
*Were there any unnecessary extra sensory stressors (e.g. music in the background, other people having a different conversation closeby, disturbance of light or smell, ...)? (that's a big one for me - makes my brain bounce all over the place, so I keep them to a bare minimum)
*Were you sitting/standing up? (you could try always sitting/laying down while having a conversation)
*Did the conversation last very long? (maybe next time cut it short?)
*Was it over the phone or in person? (phone for me is more exhausting - when talking over skype or sth similar I can lay down and don't have to keep my arm up)
No idea if you can relate, just my 2 cents (or pennies

).