I have this too. Are you by any chance on immuno-suppressants such as azathiaprine? I am, and I wonder if this is the cause?
I am highly sensitive to the sun, but I always have been. There are some natural sunscreens that can be found at health and vitamin stores. There is also some natural sunscreen that Dr. Mercola's website offers. I get itchy, even if I don't burn. But, since I burn easily, I avoid the sun at its peak hours. Since I have chemical sensitivities, I don't use the commercial sunscreens at all. I have to be careful even with natural sunscreens, since I have other allergies as well. Fragrance-free doesn't really mean that the stuff doesn't have some kind of scent, it just means that it doesn't have any ADDED scent to the stuff.
When I go out and don't have any sunscreen, I carry a big yellow umbrella--during off peak hours, unless I absolutely must travel during its peak hours. I hold the umbrella where I feel the sun most directly on my skin to reduce the amount of sun exposure. Back in my great-grandmother's time, it was common for many women to walk around with long sleeves and to carry parasols. Since no one makes parasols any more, I use the next best thing. I refuse to wear long, hot sleeves, though.
For the itching and hot spots I'll use refrigerated aloe vera gel to cool the skin. This works even if I don't have an actual sunburn. A friend told me about using straight undiluted white vinegar on a recent sunburn that I had. It is an old folk remedy. It worked very well. I stopped getting redder and I didn't get to the point of peeling and it greatly reduced the amount of itching that I was feeling.