I am lucky I guess. I work in a call center with really great supervisors. I keep them informed of medical problems. My dr helps by giving me documentation if needed. For example: dr wrote several years ago that I could only work 6 hrs instead of regular 8. No prob and since I have a lot of trouble in mornings, they gave me a 2pm-8 pm regular shift. I miss a lot of work due to illness and pain, they sd to give note from dr. I always miss more that I am supposed to in a 6 month period. A little prob, but they are ok with it for the most part.
I suggest working with your drs and get letters stating any accomadations you might need. Frequent breaks included. It would be harder for them to fire you due to disability act with those. If you have a human resource dept maybe talk to them. Good luck. That said: I stress out a lot and am always afraid of being fired but one of my supervisors sd not to worry so I am trying not to. See other thread.