My Minpin Is About 13 Yrs Old She Has Mast

My minpin is about 13 yrs old she has mast cell cancer..3rd operation few weeks ago and they put in a drain he removed a lymph node in groin area the surgery healed well but we know there isn't much we can do and no more surgery but the hole where the drain was is still leaking and it seems to irritate her skin really bad. Now they say that area may never close. I'm just so confused.