Hello,
It can be due to contact dermatitis or pompholyx. Apply some calamine lotion on the affected area and keep the area well moisturized. Try taking some antihistaminic like Benadryl. You can also apply 1%hydrocortisone cream on the effected area. Try taking Vitamin C along with this treatment. Vitamin C is a general anti-allergy supplement. If the symptoms persist then oral steroids are needed for which I suggest you to consult a doctor.