Oh really? I was told not to do any water changes for a full 7 days after adding the Bio Spira.
I noticed later tonight that Spartacus's tail has shredded more now. I was going to give him one more day but at such a high ammonia reading I just can't chance it. So I filled my vase with water, treated it with AmQuel+, Novaqua+, and a small amount of Stress Coat, floated him for about 18 minutes, then released just him (not the water) into the vase and treated him with a small amount of Bettafix. This has gone on long enough. He's going to stay in the vase for 7 days while I treat with Bettafix, and that time should give his 5 gallon a chance to cycle fully. I have 2 snails in the 5 gallon so there will still be some waste produced to keep the cycle going. Hopefully by then he'll be better, the tank will have cycled, and no more fin rot. My other Betta lived for well over 6-7 years in that vase and no, it didn't need a heater because the water stays a few degrees below the room temperature, so if you keep the room warm the water will be too.
I'll give an update in either a few days or a week to let you know how everything worked out.