Hi welcome to Health care magic forum. the eruption you had appears to a viral infection called herpes
infection which form on the cutaneous nerves and leave damage to the nerves causing permanent pain. It is not late consult a dermatologist
, he will examine and give anti viral drugs to cure the underlying infection and hence the pain.
Besides i advise you some diet recomendations as avoid taking potato, other tubers, tomato, coconut, egg and sea foods which tend to increase the pains.
Take more of green leafy vegetables, pulses, sprouts, milk, meat, and dry fruits to have resestance to the disease and pain. Wishing for a quick recovery and thanks for calling.