Hello, Welcome to healthcare magic. From your history and description, it seems to be that you are having a condition called as Polymorphic light eruption. It is an allergic to the UV- rays from sunlight, as you have rightly mentioned. The only sure way to prevent this is to prevent UV exposure as much as possible. Once you develop this condition, it could last from 6 months to sometimes 2 years if you do not prevent the triggering factor, i.e. UV rays. You should also remember that the occurrence of allergy does not depend on the amount of time you spend under the sun, even a 2 minute exposure can trigger the rashes. You could use a broad spectrum sunscreen with SPF 30 and above on all the sun exposed areas of your body every 4 hours. Use a sunscreen even on cloudy days and in winters as UV rays can penetrate through the clouds and is also present in cold wintry days. Physically protect yourself from sunrays using an umbrella, broad rimmed hat, full sleeve shirts, etc. This is extremely important. For the rashes, you can use a mild steroid like desonide cream twice day for 10 days. Hope this helps you. take care.