whats the mysterious force?
and why does it kick you out randomly?
That is the ‘Wind’ It’s a feature based from the PMD Series which stops you from staying too long on one floor. When you see “Something is Stirring” Then you should find the stairs pretty quickly.
To add to what kirk said, the wind is there is stop people from abusing one floor, for instance if you get a monster house and you stay there to train, or to get a certain pokemon, that would be abusing.