Help!!! ADA Reasonable Accommodations?!

So 2 years ago, at the age of 31, I had a pretty bad cerebellular stroke. I recovered really well physically and don't think I had much mental deficit - never had any sort of cognitive therapy afterwards or anything. I returned to the medical field last September. Recently I have been struggling with a lot of mental things - recall, memory in general, mental fatigue, focus and concentration, multitasking, etc. I started a new position with an Internal Med office in May of this year where I am rooming for a doctor, and at my 90 days had the worst review of my life! They are telling me that I am not keeping up with my work, not returning calls from patients in a timely manner-putting their health at risk, and on and on it goes. Despite the fact that I have been working 2-3 hours overtime everyday, with no lunch breaks or bathroom breaks or anything, they are telling me that I need to give more, work harder. I am giving it my all. I am now doing Occupational and Speech (cognitive) therapy per my PCP, and they also want me to do some more physical therapy.

So while I am working on that I am applying for accommodations. They rejected my first application because it was "too vague" - said that I needed help with calling patients back and more time to complete tasks. Does anyone else out there get accommodations at work??? What can I ask for that is considered reasonable (other than more breaks during the day)? It is incredibly helpful when I have another person helping me and takes off some of the stress because I don't have to worry so much about the multitasking. But is that reasonable? I would say not. How else can you ask for that, without asking for that?! I really need some ideas!!!!!