Hi Deane,
Sorry to hear what your mum is going through right now and sorry also to hear that she is back in the hospital again. I hope that her doctors get to the cause of her issues asap and please keep us updated on how she does. As to the difference in BP from her left and right arm, I have never heard of this either. If someone has heard of this or has any info to share on this I am sure that they will do so here. Stay strong Deane and know that we are here with you.
My best wishes to you and your mum,
Gavin