You might want to try a Facebook group called Descendants of Andersonville Prison. I think there was someone on there recently who was looking for info on someone from the 69 NY.
And I've never come across cerebritis as a cause of death before. My first thought was that it may be a misreading of "Sorbitus" which was one of the top three causes of death at Andersonville (cerebritis is a brain inflammation; sorbitus is another word for "Scurvy.")