As others have suggested, Lee, now may be the time for you to just go with what's in front of you, one day at a time. If it doesn't feel right to be taking photos, don't take photos. It'll all come back with renewed passion when the time's right. However, could I suggest - and I hope you don't find this indelicate - that perhaps you could take lots of photos of your parents. From what you're saying, they have limited time to enjoy their lives with you and now might be a very good time to have a camera with you when you go and visit them. I remember a newspaper article many years ago about a photographer whose husband was dying of cancer. She took hundreds of shots of him throughout his illness and even after he'd died. People were shocked but I think it was a beautiful thing to do. It was her way of dealing with the emotional turmoil of losing the one she loved. Photography was a strength she had that she didn't have to think too much about but which got her out of her head for a while (and left her with some wonderful images after he'd died).
Is this something that has any appeal to you, I wonder?