Thank you for the query.
First of all you should know that usually cancer in such area does not cause acute pains for a long time. If this lump is near groin region it can be an inguinal hernia
. It can get bigger while standing and coughing. If so, surgery can fix it.
Such painful lump can be also sebaceus cyst
. This is benign soft tissues lump which get painful if gets inflamed. IT can be also removed with surgery.
The best way to have it diagnosed is to perform ultrasound
of this area.
Hope this will help.