Well, I'm pretty sure the ammonia and all that is okay, because everyone else is alive. The guppies, the goldfish, and the other two snails are really happy. Spock looks like the picture of health on the outside, and I've watched him when the lights are off, he doesn't do anything at all. The temp is as warm as it always is. I've been taking good care of him, and he just started to move recently, but after a couple of inches he stops and goes back into his shell.
Spock is a very cowardly snail. When I first met him, he wouldn't come out of his shell for an hour. But this isn't just cowardly, it's more like sickly.
I think he's gonna make it if I just show him a few more days of TLC. Thanks everyone, for your care and support
P.S. If he gets any worse, I'll report back.