Suggest Remedies A Raised Painful Boil With Dark Fluid Discharge On The Buttocks

I am 32 yrs old and My 18month old son has a risien or boil of some type on hz bottom rite where the crack of hz butt begins it has ben there for a lil over a week an it was very large and very hard it has drained a very dark im color blood along with pus 4 seperate times its size has went down sum but is apparently still full of pus an blood it is very painful to hmm I have not assisted in any help of the draining what can I do an will it ever go away he is on antibotic for a middle ear infection now.