Welcome to healthcare magic.
From your description, I would consider the possibilities of an acute photo toxic reaction , porphyrias and hydroa vacciniforme.
You have not mentioned your age, who would help assess better.
Photo toxic reactions occur as a reaction to a drug/ allergen. Are you on any medication?
Porphyrias are a big group of disorders which require a detailed work up.
Hydroa vaccinforme is an allergic reaction
to UV rays.
All the disorders need to be considered and a detailed work up is necessary to come to a conclusion.
Hope this helps.