Disability Discrimination

I have been employed for 8 years in the same postion as an office assistant and have been recently moved out of admin support. (I was told that I
wasn't admin support and do better at data entry and special projects) I was placed upstairs and out of the public sphere and am by myself most of the day. Someone in the co. new I was disheartened & wanted to know why... She told me "they couldn't tell me" I asked what she meant by that and she said they couldn't tell me because there could be legal issues. I was moved out of a job I had been doing for 8 years with excellent preformance because my grammar wasn't up to what they wanted. I at times used double negatives and used the wrong tense of verbs .
They did not come to me and offer to help with this nor said to me that I needed to correct it. They said nothing! I believe I was an embarrasment to them. My pay wasn't cut just my job duties (considerably) I therefore believe they will cut my job (what little I do) and say my position is no longer needed.
I used to have epilespy until I had surgery 15 years ago. I still have trouble with my memory and have lost some of what I had retained before the surgery. (gammar usage) I had scar tissue removed from the front of my brain where the memory is. I still have my medical records which include a neuropsychological report.(evaluation) I thought the discrimination was over with but this is worse than when I did have seziures. I did tell them when I was hired about my epilespy and surgery and that it did take me some time to learn things. What legal rights do I have and what can be done about this?
This is disability descrimination. Please help!