A deputy was sent to the Medical College of Georgia Hospital emergency room around 10:45 p.m. at the request of a caseworker with the Department of Family and Child Services.
The suspect, Darian Thomas, 20, told the deputy the boy had run into a wall Monday, causing the child's eyes to swell, a report states.
Thomas reportedly told the deputy that the boy showed no ill effects Tuesday or early Wednesday, but could not be awakened Wednesday evening after vomiting.
Jail records show Thomas, of the 3500 block of Shadybrook Drive, was arrested Thursday at the sheriff's office on a charge of cruelty to children in the first degree.
A spokeswoman for MCG said Thursday evening that the child's condition could not be released because of privacy laws.