Hi Nikkinak,
It must be so hard to watch your son suffer
I hope they can quickly determine the cause of this!
Make sure that your son is being seen at a hospital with expertise in these diseases, as they are both rare. It's always worthwhile to get a second opinion. A person can have AA and have a normal absolute reticulocyte count and/or absolute lymphocyte count. NIH believes that these are positive markers for response to IST. Given time, if he has AA, these will likely track down. Also, a person can have MDS without genetic abnormalities. What specifically does the BMB report say? Does he have an empty marrow? Has his doctor done extensive testing for other possible causes?
I remember having bad aches in my legs and neck. For me, it was when my blood cells were increasing.