So sorry about your frog . I see from some of your older posts that he seemed sick on a couple of occasions, perhaps it was a long term neurological issue based on the symptoms, but only a full necropsy could give any answers, and even then it might not. We could do a full analysis of the conditions to pinpoint if there were any things that may have been overlooked, but again, that could only come up with some maybes. It may be something to go over if you decide on another frog in the future but for the time being, I would say just mourn your loss, and remember your wonderful frog.