Can i Sue or just let it go?

I have been working at the hospital for 5 1/2 years i was told that if you call sick 13 times in a year i can get fired but thats not fair i mean can i sue? cuase i have a permanent illness its hypoglocemia (low blood sugar) and burnout too , in the previous jobs i worked i never got sick or missed work but it seems like this hospital is getting me sick is it my scheduele? 3pm-11:30pm or is it just me that getting myself sick? this may be confused but all im asking is should i sue them if they fire me for beein sick 13 times on a year?