I'm going on a flight from Australia to Europe in a few weeks and am panicking. My IBS has been playing up really badly the last week, the closer it gets to it.

does anyone know if there are usually spare seats on a plane? I'm worried that if someone near us is sick, will we be able to move? Also, do they clean the toilets often? We're going with Singapore airlines.

and is bad turbulence common? I'm worried about the plane dropping and it making people airsick

any advice would be really appreciated.

thank you