Thanks for the query to H.C.M. Forum.
This is a lump filled with pus call as PERI-ANAL abscess
Reasons may be many but bacteria's type may be streptococcus
, staphylococcal .
May be fistula ( less chances according to history of illness in query).
The ice pack massage
, antibiotics,anti inflammatory drugs will help you.
Since you are on vacation , so take aceclofinac 200 mg controlled release tablets according to pain and swelling.
Rest is also good for you .
Lie in prone position , so it will not get inflammation any more.
Get in blood for diabetes
Stool examination also important.