I changed the battery and it won't shut up
That just a part of riding roller coaster you. Your body feel forces as you go up and down. The higher or steeper the drop you can always expect an increase. The feeling never goes away, some people like the feeling and others don't. I do recommend that you start with a smaller coaster so you can get your body warmed up. You can warm up but its not really something you can get used to its just goes with riding roller coasters.
Any foreign material in the betta's water could make him sick. I'm glad you changed his water; that probably helped. Bettas often lie still, so he may be just fine, as long as he isn't laying on his side or upside down!.
