K.C.
Brock seems to be very aware of his health and the problems with his health. No matter how one tries to be careful about what is said around a child, they pick up things, put 2 and 2 together and come up with their own answer. They hear it out in the community or when everyone thinks the child is asleep or outdoors and can't hear the discussion. You can not hide things from them forever. It's better to deal with fears head on, carefully worded, of course. I have 3 suggestions......
1.) Listen to the child's fears, address what you can and what you can't, tell him so, but that you will do your best to find the answer.
2.) Go to the Priest or one of the Sisters, that is what they are there for. Either they can talk with him and address the spiritual side of this or can find someone that can.
3.) Another option is to talk to the doctor, if there is concerns maybe it is time to be open with Brock about what is going on with his health. Some doctors are great with explaining things to kids. Or I am sure that he can recommend a social worker or counselor that can help Brock through his fears.
My prayers are with Brock and the family.