Hi Kellie

Have you explained to your son in simple terms what's happening with his Grandfather? He's obviously noticed there's something wrong with him and he's maybe scared and confused. If you have already spoke to him i think the only thing you can do is keep talking to him and reassuring him. Have you also thought that he's scared that if this can happen to his Grandfather it can happen to you too. He's maybe scared that he's going to lose you. That tends to be the way kids think. It's happened to Grandpa it can happen to Mom/Dad too.

Good luck and I hope you get some more helpful responses soon.