Hi, Welcome to Health care magic forum.
It appears that you have some infection, even before the intercourse, and so you had the pain. It flare as the days pass.
I advise you to consult a dermatologist
for diagnosis and treatment. You may have to exclude the STD
Take more of green leafy vegetables, pulses, sprouts,and
protein rich foods to hasten the recovery.
Wishing for a quick and complete recovery. Thank you.