A doctor came to the house that day and examined the child; he seemed fine.
But six days later, Spears and Federline became concerned and took Sean Preston to Santa Monica-UCLA Medical Center to have him checked out, the source adds. No serious problems were found.
Spears, Federline and their son are back home and doing fine now, a second source tells PEOPLE.
After the hospital visit, child welfare officials visited Spears's home accompanied by a sheriff's deputy.
According to Glafkides, the visit lasted about half an hour and no police report was filed.
The Sheriff's Department could not release any further information, and the Department of Children and Family Services generally does not comment on cases due to confidentiality laws.
"While there was an automatic report by the hospital to the Department of Children and Family Services, DCFS immediately responded and determined there was no problem and no reason to open a formal investigation," Spears's attorney Marty Singer tells PEOPLE. "They determined that the parents were not involved in any injury and that nothing improper was done within the home."