Workers comp

I'm about to go to work, my back will never forgive me 😔

I did something to my back on Friday, and it's still messed up. My brother is telling me to ask to open a comp case so I can get checked out (It was work related and I don't have insurance) but I'm scared that if I tell my boss something might be wrong she'll either think I'm incompetent at my job, or am dramatizing the pain just for the case.