Simple Breast trauma, or possibly more? (photos)

Hello. 33 y.o female. No children (never pregnant). Just noticed this on the underside of my right breast. The skin around the exposed skin is darker, but not a scab. I did wear a waist trainer yesterday that was apparently too tight, and caused the marks on my side (posted below) that I haven't put back on. I wore a Sports bra and don't see how the trainer could've mad contact with one of my breast (me not both) so I'm feeling like this is an older occurrence as it not sensitive to touch.