Thanks for the query.
Infection should be managed by two most important steps:
of the pus
2) Appropriate anti biotics: topical and oral
Since you have not responded well to the ones you have had, you should so in for a culture and sensitivity testing of the pus inside the bump.The other sites of colonization of the bacteria need to need examined as well.Antibiotic therapy should be started only after this result.You might require to apply / take oral for a slightly longer period of time if required.
Hope this is helpful