Don't worry...you are suffering from viral herpes causing this problem... Specific medicine available for good control... Treatment depends on the severity..Do direct online consultation for detailed prescription by sending photos.

Dear friend the explanation provided by you looks like a rare condition known as porphyria cutanea Tarda. in this condition the skin exposed to sun can have blisters and it may mimic the lesions of herpes or cold sores . it’s important that you protect your skin from sun exposure and also apply a good quality sunscreen. Use a Hat / Umbrella / gloves or any physical meat or to protect the skin from sunlight. you may also have to contact hepatologist liver specialist and your dermatologist because there are certain medications to manage this condition. wishing you very good luck and healthy skin.