Still really missing this guy, but at least I know what happened now. The Necropsy along with the cultures showed an extremely aggressive and drug resistant form of RI. He'd most likely been carrying it when I brought him home as none of my other snakes had it. Once it took hold, he was gone in a matter of days. Take this as an object lesson people. Quarantine procedures are so important. This could have easily wiped out my entire collection. Better times ahead...