skin infection-ASAP!

Hello, my baby is 19 month- week and half ago he got skin infection on his leg close to his crotch, the lube results showing that the infection happens by Bactria, they open the infected place and took out as much that they could pus, and put him on antibiotic and some cream for 10 days we wash the place with warm water, and tried to clean pus as much that we could, but , now the wound is close and we still filling some kind of pus under the close skin, , we Willi don't know what to do, please let us know if you thing the under skin pus will go away by himself, or we need to open the place again my baby was suffering a lot and was under lots of pain, please let us know if we can avoid opening the place again thank you so much!