Back acne? Management

Lately... maybe around the back and shoulders??

That part... something that can't be cut, like a pimple?? or acne??? or other problematic skin conditions seem to have developed...

It seems like a skin trouble caused by secretions or discharge...

Thinking about it... exercising and not taking a shower seem to make it worse...

These days, it's a bit cooler, so I walk ten thousand steps and then don't take a shower.

I just take a shower in the evening whenever I sweat a little. I don't do morning workouts, shower, walk ten thousand steps, and then shower again.

Then... it seems to be getting worse...

It doesn't disappear,,, it sinks,,, then rises again,,

Could this be... really, is it because of the exercise as I thought??

Hmm... how can I make this disappear?