Delayed Healing- Tummy Tuck (Photo)

I have a tiny spot on my tummy tuck incision that will not stay healed. It heals over and then a few weeks later, the same spot fills with a yellow liquid that turns white and my surgeon ends up cleaning it out and restarting the healing process. He has already done 1 revision on the area and it is coming up on 1-year post op. All cultures have been clear of bacteria and we are both confused as to why it won’t stay healed. Looking for any advice- have tried oral and topical antibiotics each time