Today I haven't slept all night. I feel horrible, like I'm about to pass out any minute. I told that to my boss to which he told me that basically I have to find someone to fill in for myself and he's not going to do anything. 5 minutes later I get another call from him where he tells me that no wonder no one wants to fill in for me when I haven't filled in for a colleague once when I had 2 days off after I had about 9 12-hour shifts (some 10 hours). So no one can fill in for me. I'm forced to stay at work feeling an absolute garbage. Is this legal?