Lewis Mullins, who lived with his parents in Maltby, in Rotherham, died in April last after being seen by both an NHS Walk-In centre and twice at Rotherham Hospital in the three days before his death. He had been suffering from chickenpox.
Heather Kolar, a medical law specialist at Irwin Mitchell, representing Lewis' family, said: "His parents were distraught at losing Lewis just days after his first birthday. He had been suffering chicken pox but became more seriously ill in the days leading up to his death.
"His parents feel they have been told very little about what happened to Lewis and are seeking answers as to how he died."
The inquest is being held at Rotherham Magistrates Court and is due to finish today.