HR is Asking for Doctor's Letter?

I was diagnosed in April of this year. It has been a relief to finally have a name to go along with all the physical symptoms and issues I have been dealing with for the last few years. MG, who knew? Not my family doctor but I appreciate him anyway.

When I approached him with my symptoms and complaints he had no idea BUT...he did not stop there. He sent me to referral after referral and for tests after tests until one of the referral doctors figured it out and did whatever specific blood test was needed to diagnose me. Bless both my family doctor who accepted that he did not know the answer and did not let that stop him, and the neurologist who finally figured it out.

Now we are trying to get the MG under control

I have good days and bad days.Days where I can operate almost normal, and days where the symptoms are bad enough it is not safe for me to drive. Muscle weakness, twitching, drooping eyelids, etc.

When I wake up in the morning, sometimes I feel with the symptoms that it is really not safe at that time for me to be driving to work. Thankfully I work in IT and 99% of what I do can be done from home with a good internet connection and a Virtual Machine connection to my workplace.

Since my diagnosis I initially tried during bad days to make it into work regardless but sometimes it was really not safe, when the symptoms are bad or when a flare is occurring. So I approached the Director of IT and got unofficial permission to notify him when it was not a good idea for me to come in for work and he would allow me to work from home. But he warned that if it happened often enough that he would have to get HR involved and it is happening often enough that it has reached that stage.

HR wants a letter

HR wants a doctor's letter explaining what is happening to me and that some kind of accommodation is necessary for my health and safety. HR wants details of why I need it and what I am asking for. So I have to get the doctor to explain MG in general and the symptoms and flares etc. Has anyone else been asked for such a letter? How much detail do they really need?

I am not lazy. I love to work. I am looking for either a scheduled work from home days (Maybe every Tuesday and Thursday) so that I do not have to be exhausted every single day with the effort of getting up, preparing for work, driving to work, and starting the day already tired from that effort. If I have work from home days scattered throughout the work week, it makes the days I do have to go into work a little easier and less consecutive days of draining effort.

Does that make sense? Am I asking for too much?