> Edit: that being said, you did FU by involving your mother. You should be able to solve your problems.

You may have missed that OP is a minor.
It is the legal representative's job to verify that OP's employer is not endengering OP's safety and as such the mother has all the rights to call out the manager.
If the minor is so sick they couldn't stay at school, they are not well enough to go at work.