I agree with the stress speculation.
Even when what I call "Unfelt" stress is present.
Things like doing everyday things. Going to work.
Just Unfelt stress.
I know for a fact stress was a big factor with myself.
I could go into it. But I won't. Well. A little.
Once I got rid of my problem all the stress I felt there was gone.
I cannot say it was for anyone else.
Richard