Hi,Dear,Thanks for the query to HCM.
In My opinion-the lump you have is of Chronic Boil of the right butt cheek.
Advise-
Consult a doctor and take following tips-
a-Tb
NSAID x 5 days time would resove it.
b-If not CBC / urine would confirm the severity of infection n cause if any .
c-Antibiotics -x 5 days -if it still grows.
d-IF no relief-Show it to ER Surgeon,who would treat it By Surgical drain with wall scrapings of the chronic
abscess on your buttock, if need be.
Currently-
I feel you have subacute attack and need treatment with your ER Surgeon.
You should plan its Excision as its Chronic Boil lump and needs to be removed to stop further illness from it.
Hope this would help to plan treatment with your doctor.
Hope this will help you to take further needful steps and
to treat this emergency.
Wellcome for further query in this regard.
Wishing you fast recovery.