The only things on your list that may have contributed to his illness would be not using a water conditioner/he should have been fed daily to everyother day/temps could stand to be higher at 79 to 80 during the day/moss can be bad if they ingest it causing impaction/a day lamp could have helped raise day temps. I think 63 may be too cold 70 to 75 may be better.

Cram yourself with research it is a must before even owning a frog. You are already in the right place to learn what you need and we are all here to help you. He was beautiful Ian. I'm very sorry.