8 week old sleeping 12+ hours

My 5 year old gave the baby a cold. He's already been to the pedi and rsv negative. However hes been sleeping for a solid 12+ hours straight. I've had to physically wake him up. He's not dehydrated or running a fever. When he is awake he's so happy. I called the pedi again today bc that length of time concerns me. All they told me was to continue doing what I've been doing ( suctioning, humidifier ECT) and wake him up around his normal schedule. Is there anything else I should be doing? I feel like i should be more proactive.