Abscess/Collection That wont go away

I have an abscess with infected collection that is taking forever to go away. I already had a drain put in which got rid of most of the fluid but there seems to be a small left over. I am now on two antibiotics that I hope will do the trick but I am working against the clock for my final surgery. Has anyone had any experience with something like this? How long did it take to go away?

Im curious why that would make a difference?