Hello,
Welcome to health care magic
What your husband is having could be infected pilonidal sinus or infected sebaceous cyst or furuncle/abscess. The pus collection has ruptured leaving behind a hole. He requires a course of oral antibiotics and dressing of wound. Kindly consult your primary care physician for the same.
Hope this helped
Take care

Hello,
Thanks for the query to H.C.M. Forum.
As described , it may be a staphylococcal infective pyoderma .
Fistula in anus,
Hemorrhoids .
As physical examination is very important , so please consult a surgeon and get his opinion.
Get in blood for eiosinophils ( worm infestation), sugar level
Good luck.
Dr. HET

Hello Good Evening,

This is looking like Pilonidal Cyst, also referred to as a pilonidal abscess, pilonidal sinus or sacrococcygeal fistula, is a cyst or abscess near or on the natal cleft of the buttocks that often contains hair and skin debris

-One proposed cause of pilonidal cysts is ingrown hair.
-Excessive sitting is thought to predispose people to the condition because they increase pressure on the coccyx region.
-However there are cases where this can occur months after a localized injury to the area.
-Moisture can fill a stretched hair follicle, which helps create a low-oxygen environment that promotes the growth of anaerobic bacteria, often found in pilonidal cysts. The presence of bacteria and low oxygen levels hamper wound healing and exacerbate a forming pilonidal cyst

-In the treatment part there are antibiotic therapy, hot compresses and application of depilatory creams

-In more severe cases, the cyst may need to be lanced or surgically excised (along with pilonidal sinus tracts).

So go to your local surgeon and get diagnosed and treated.

Regards,

Dr. Naresh Jain.