My managers are awful

I called this morning to call off my shift tonight because im not feeling well, but the manager on duty was too busy. So i texted my GM and told him. He told me to try calling again, so I called again and the manager on duty told me I need to go get medicine so I can feel better to work my shift. I texted my GM again confirming that I don’t feel well enough to come in tonight and he hasn’t responded. My shift starts in 40 minutes and idk what to do 😭