Hi, thanks for posting your query
you seem to have a boil on your right shoulder,which is pus filled . Due to collection of pus the surrounding area is red hot and painful
The exact size of it is not mentioned , its better to see a doctor for proper examination.
You need to start oral antibiotics
and local application of mupirocin
The pus has to be drained by a minor procedure incision and drainage
, by a doctor. This will decrease the pain significantly
Hope this solves your query