The experience we had with my mother and Coumadin was a roller coaster, to say the least. Her dr had tweaked her dose where it was slightly smaller every third day. Fortunately, she was in assisted living and an LPN supervised her meds closely. All was lovely, until she started having swallowing and appetite issues and started losing weight. This threw her coumadin dose all out of whack and she was given vitamin K injections to thicken her blood. So I'm with the other ladies about protein drinks and other supplements and add a suggestion that someone monitor her weight. Does radiation suppress appetite? I can't remember.
You are doing wonderful work, being an advocate for your mother's care. Keep us posted about what you find out.