There are several different types of infections a Ball Python can get...some you can treat and it will go away but can and will lay dormant....but most never go away...
Your best bet is to contact local breeders in your area and ask them if they know any good reptile vets....take it to the vet and have them do a culture to test what is the underlying cause....some infections are cause by poor husbandry...some by stress and some by serious illness...most can be treated with doses of Baytril some need Flagil or Amikacin but from what you are describing it sounds air born which has been known to wipe out partial or whole collections with no cure....you should in the future always quarantine new additions for several months before adding to you collection for the reason you posted this question.
Good luck...
Travis
Lair of Dragons