Seems like every year I get bites similar to this, all within 6 inches of my pits or groin after being outdoors after sunset. I believe they are spider bites and have been thinking lately they are the little red spiders, maybe mites too. I treat the bites with gel benadryl to reduce swelling.
LOL a couple years back I went in for my DOT physical and that includes pulling down the pants for a hernia check. I warned the young female doing the inspection that I had some bug bites down there. Shoulda seen the look on her face….