What do u call this mental illness

[hollow]

Let's say i go for a walk in a park or forest

When i am all myself there i walk very relaxed and chill

But the second i see from afar a normie coming my way or when i hear a normie speak somewhere i tense up and walk very stiffly all of a sudden

I've been told i walk like a ps1 character and that i keep my back extremely straight

This happens less extreme when i am walking besides somebody that i know