I'm late to these comments but hopefully this will help someone. I massively self-harmed when I was younger. Thankfully, I'm now in a much better place, however, I still - 30 years later - am left with the aftermath of very large scars everywhere. Fortunately, there are more options than when I was younger. There is a industry movement towards clothing that protects you from the sun which also have cooling properties built in. I have a few SPF long-sleeved shirts, I have "cooling arms" meant for golfing, cycling, etc. I also (female) have loose, airy "boho" blouses in summer colours with camisoles underneath. Anyone who asks I say I'm sun sensitive and it's generally accepted. And just a final word to anyone still self-harming, don't give up on yourself.