What Causes Low Sodium Levels In The Body And Itching Sensation While Treating CHF?

My mother is 83 yrs old, a mild diabetic with a history of multiple falls. She has suffered multiple concussions, a fractured hip, (2) pelvis fractures, (3) broken arms, all due to falls. Both knees have been replaced, a left hip replacement and surgery to repair a spiral right hip fracture with a rod and screws. She was diagnosed with CHF with 10% fracture. She is in assisted living and has suffered (2) falls recently. She was admitted to the hospital after her last fall and was diagnosed with to low sodium. She is also complaining for itching. I am trying to understand the evolution of her illness or are these issues unrelated to the CHF? Is there information you could provide that will help with her continued care?