She requires strong pain killers as she is having a condition called post herpetic neuralgia.
She can take Paracetmol or even Diclofenac tablets and apply capsaicin ointments
Next Steps
If not subsiding consult your doctor and get stronger pain killers for her which can be bought only using prescription.
Health Tips
This pain can persist for sometime and she can get this infection at exactly same site when ever her immunity goes very low.