Laurie ~
I'm sorry to learn that this has happened to you but frankly, I'm not shocked that it has because we've read about things like this happening before. Apparently, your honesty has not been rewarded. Your employer is attempting to lock you into a position where, if you fall down in your work or seek to take a LOA due to issues connected to your AN, they can deny you the LOA or terminate you for 'poor performance' and use your doctor's statement that you're capable of doing your job as a shield against any future attempt by you to use the labor laws (or sue) on the basis that you were physically unable to work at full speed and that you informed your employer.
Unfortunately, this kind of action by an employer usually indicates that they are seeking to separate you from the company because you've become a 'problem'. It stinks and is heartless but it's also quite common. It happened to my wife. Fortunately , she had disability insurance that protected her income although she was forced to apply for Social Security Disability benefits (she was successful). As they say: 'business is business'
I truly hope this unpleasant work situation can be amicably resolved, Laurie.
Jim