Hi LGL!
I am so sorry your BIL is suffering.

I know this also means others are suffering, too.
There are so many potential causes of illness in this case... it would be too difficult to even try to guess on this! I am glad some specialists are taking care of him and are trying to help.
Just FYI, I am not sure if this interests you or not; however, anyone may ask for prayer, for positive thoughts, etc. if they so desire... by going to the "Spiritual Support Forum!" (No worries if this does not interest you. Just want you to know its available should you be interested.)
I hope you stay in touch! Please let us know if we can assist you in any way during this difficult time.