You have developed 'Polymorphous Light Eruption'. Its a kind of allergy
to visible light. I am sure the patches are limited to the exposed parts of the body only. The red is the eruption which is accompanied or preceded by itching, and the white patches are the post inflammatory hypo-pigmentation.
The only way to manage this is a good broad spectrum sunscreen. Use it everyday on all exposed parts of your body and re-apply it 3 hourly. This needs to be done everyday irrespective of whether you are indoors or outdoors.
Try to avoid stepping out in the sun between 10am and 5pm if possible. Try to wear full sleeved shirts as protective clothing. Prefer a car over a motorcycle while travelling.
Also you can apply Caladryl
lotion to the itchy red patches to sooth them and maybe prevent them from developing a post inflammatory hypo-pigmentation. You can also take oral antioxidant capsules
and have a diet rich in colourful fruits and vegetables to improve your immunity towards light and UV damage.
Keep looking beauliful,