Here are my previous panicy posts:
Thanks to the quick and generous advice from everyone on this forum, Roy is making a steady recovery from his ammonia poisoning!
His ammonia burns (which manifested as white patches of missing scales on his spine and under his chin) are healing, his fins have unclamped, his mild bloat subsided and he's eating like a little piggy once more.
What did I learn from this? Patience is a virtue in fish keeping! Every fish is different and just because it happened to Roy doesn't mean it'll happen to all fish, but fishless cycling is really the way to go. It virtually eliminates the chances of your otherwise happy healthy fish receiving ammonia poisoning. I did as much research as one possibly could before switching him into a new tank, but fishless cycling is still not a very widely understood concept, and I almost learned about it too late!
I'm posting this because I hope it'll help future betta owners, as well as ones that may be experiencing this type of disease right now. Again, not every fish will experience these symptoms, but if you move your fish to a new tank (or bring him home for the first time!) without cycling it first and he begins showing signs of illness within a few hours, he's probably suffering from ammonia poisoning!
The good news is that if you catch it quickly, your little guy CAN make a full recovery. A lot of people told me to move him to a smaller hospital tank, which oftentimes is the best thing to do, but in this case I did a 50% water change in the main tank daily for a few days while also testing it several times a day for ammonia spikes. Every time I did a water change I treated the new water with Prime and aquarium salt. Roy started improving within minutes of the first water change and only got better over the next two days.
I'm now doing a 50% water change at least once a week with Prime and aquarium salt for an 8 gallon tank as maintenance and monitoring the water parameters regularly.
The moral of the story is do your research first, seek help the moment you notice a problem, don't rush into harsh medications, and DON'T GET SLACK ABOUT YOUR MAINTENANCE.
Thank you to everyone who helped Roy and myself, I hope other betta owners or owners-to-be can learn from my mistakes, and for those you have lost your friends to ammonia poisoning, I'm so sorry for your loss, but it's never too late to learn.