PE is not a frantic endeavour. It takes patience, awareness and control. None of which you seem to be showing as strengths.
You jumped to the conclusion of hard flaccid days ago then hours later decided it was cured and jumped back into over training. Frantic.
Take a few weeks or more off any PE exercise to rest what may or may not be a physical injury, calm yourself, refocus and read about everything that interests and worries you. There are many many months worth of research here that could be done before ever attempting an exercise.
I am not a fireman, but I assume new candidates don’t jump into the heart of a 5 alarm burning building to only then start asking questions about how to fight a fire.