Will Medicare pay for me as caregiver for my mother who cannot walk?

Where do I find this information? My mother has had 3 strokes, one of which resulted in hemianopsia (sp). She has been going through chemotherapy and radiation treatments due to a diagnosis of an aggressive form of lung cancer. She has developed a significant blood clot in one of the arteries in her left foot and cannot walk. I have been residing with her and my step-father during the week and home on the weekends. She is on Medicare as well as Blue Cross Plan 65. Will either of these provide for relative caregiver payments for me as I have been unable to work and if so are they retroactive? I have been caring for her since the latter part of May 2013?