Strange thing, I only feel short of breath when in my swimming pool, underwater. I used to be able to hold my breath for 3 minutes but now it's about 40 seconds. Pulse is not 48, used to be less.
I am fine when I run 7km, the only other time is when I am going to sleep.
Possibly, it is related to anxiety, although I generally feel less anxious than times in the past.