Jaundice level peaks at about day 9-10. If baby is very sleepy, consider bringing him for a check again, cos the level might have gone up.
My boy started becoming sleepy on about day 9, we brought him to check and his jaundice level was high, so we stayed in hospital together for phototherapy. And continued breastfeeding often. His level dropped after 1 day and we went home. Then no longer so sleepy.
Try latching baby on every 2 hours even when he's asleep. He may be able to dream feed.
Try undressing him in a room with no direct air con or fan, only diaper on, then feed. If he's warm and cosy, would be sleepy.
Breast milk helps to clear the jaundice when baby passes out yellowish poo poo. Just that the level would take a few more weeks to clear completely.
If worried, just bring baby back to paed yah? All the best!