It is an attack of acute sunburn
.. it will be better day by day, so do not worry.
You need some urgent medication like..i) pain killer e.g. Acitaminophen/ Ibuprophen and or ii) a short course of prednisolone
e. g. 40/ 60 mg daily for 5 day in devided doses.iii) lotion or emolient cream for skin care
You need to consult a dermatologist
urgently for better care.
Dr. MM MAhmud