Welcome to HCM.
Most likely it looks to be
fungal infection.
It usually occurs after unprotected rough sex,improper hygiene,severe scratching after perspiration.
Take proper local care.
Wash it with antiseptic liquid, make it dry and apply cream like
clotrimazole,miconazole.
Start complete course of oral anti fungal like terbinafine,fluconazole.
Azithromycin,secnidazole will be helpful.
Your wife should take Azithormysin,secnidazole,fluconazole kit.
Avoid tight undergarment.
Avoid sex till get complete cure.
You have to go for certain investigations if it is recurrent ,to rule out underlying disease.
Go for cbc,urine,fbs,ppbs,std profile,hsv investigation.
Get examined by
dermatologist and start proper medications.