Isn't it illegal for them to make me self terminate myself since migranes are a medical condition?

i work in a nursing home kitchen where I also do a job called office in which I have to use a laptop to ask residents their menus for seven hours. I recently found out that I have chronic migranes and recieved a note from my neurologist to give to my supevisor that says that I cannot work with small screened computers anymore. My supevisor read the note and said that since I am unable to do the job required of me I might have to self terminate myself. But this is untrue the office position was never a part of my first, required job, it was an add on position he asked me to do.