Assuming your in the United States, unless your unconscious or otherwise unable to answer questions about your health history the hospital has no business asking anybody else personal questions. You might ask to speak to some one from hospital admin about the issue. I would minimize discussion of the family religious issues and simply point out that you may have medical issues your mother doesn't know about and they should talk to you not here.
My guess is that whoever took the information probably didn't have any reason to believe your mother would would not give an accurate answer. Of course, that person has no knowledge of how sneaky JW's can be such situations.