It sounds to me like it's starting to re-form. Many times, the abscess will heal on the outside but not all the way on the inside, leaving a little pocket of air that can get re-infected. Hopefully you've caught it in time, though, and that's great that you'll be seeing the specialist. Make sure, if it is drained again, that you ask for it to be packed each day so that it can heal slowly from the inside-out.
"For this thing I besought the Lord thrice that it depart from me. He said, My grace is sufficient for thee: for my strength is made perfect in weakness. Most gladly therefore will I rather glory in my infirmities; I take pleasure in infirmities, reproaches, necessities, persecutions, distresses, for when I am weak, then am I strong" 2 Cor