There are many medicines that can make a person photo sensitive, it's quite common. Also many plant juices can do it, lime juice is terrible for sunburns. And me,I'm just sensitive. I keep a big hat and gloves at the door to the garden so I have the habit of grabbing them whenever I step outside

That is one thing. If you have been sunburned, just getting exposed to sunlight will give you a reaction, even if it is 7pm light, with no UV component (due to the shallow sun angle). Or it could be Omega 3 deficiency, my resistance to sunlight has become ten times better since I eliminated seed oils and started eating only meat that was grass fed.