Sorry to hear about your snake. Sounds like you were doing everything right so kudos to you for being a responsible owner!! Sometimes a snake just has an underlying issue unrelated to your care. While a necropsy is the only way to truly know, unless you need closure or something I would put that money toward another ball python instead. For every great BP breeder there are 2 crappy ones, so if you need help finding a good breeder that will get you a healthy snake that is eating just let us know what your looking for and we can point you in the right direction. Definitely take this time without a ball to properly disinfect everything for the next one.