I've recently noticed that right after I do bench press, the part of my shoulder blade that is feeling most of the pressure develops at least 3 new pimples. The pimples are pink, hard, and underneath the skin. Normally, there will be none that will grow there. It's only on the days I bench press. I don't know what to do. I'm not going to stop weight lifting or doing bench press, but I don't know understand why my skin decides to create a pimple from the pressure. It's never done that before and it only started 6 months ago.

Btw, i'm a 17 year old guy.