The fall of 1863 was not a good one for Riley. He was in the Regimental Hospital with dysentery and diarrhea.
He was admitted to the 14 Army Corps Hospital, Army of Cumberland, on 30 July 1864 and returned to duty on 2 August [edited from the original post which said "2 July" incorrectly] 1864.
That illness is mentioned in more detail in his pension record. Fortunately his pension doesn't mention the diarrhea, but it does mention something happening in late July of 1864.
These records were separate from Riley's compiled military service record.
Stay tuned.
Readers can learn more about these records on the National Archives Site: http://www.archives.gov/research/guide-fed-records/groups/094.html#94.12.3
