Reasonable Accommodation w/Dr Note

I have always worked night shifts, I like nights, I never planned to switch to days. However two weeks ago just as I was getting shift report I had a seizure out of the blue with no known cause. I was admitted to the hospital for tests and observation with nothing resolved. I've since been put on anti seizure medication but my Dr says I should switch to dayshifts. He has provided a note stating the request due to ongoing medical issues. My HR department is saying the note is not sufficient because he doesn't designate a specific length of time for this accommodation. We are supposed to be having the interactive meeting to discuss options but in the meantime I'm supposed to be acquiring a more detailed note from him. Another layer of complexity is I took a sign on bonus and I'm only 6 months into my 2 year contract. I really need some advice as to how to proceed. I don't want to go against my Dr advice and have more neurological problems. I have had a considerable increased level of stress in my life lately and I think everything converged on my system at once. I'm trying my best to take better care of myself and want to know really what I should expect to happen here.