Mmm.. central american boa from petco...
Odds are that it was a wild caught, loaded with parasites.
As fast as it went down hill, even with treatment, it may not have made it.
And it would not shock me if one of the culprits is reptilian cryptosporidiosis, a rather nasty parasite that a certain big chain has been plagued with for quite some time.
Be sure to clean its tank with a very stout bleach solution, possibly full strength and rinse it well, with plain water before using it with any other critters.
And sorry for the loss..
