Took my baby to the ER Sunday morning. He's been ill, not really wanting to eat or drink. He's not…

Took my baby to the ER Sunday morning. He's been ill, not really wanting to eat or drink. He's not dehydrated but since yesterday he still doesn't have any energy, doesn't really want to eat or drink,still. Slept all night long and I just called the sitter and he's asleep now. Idk.. should I take him again to the ER? Waiting on his Doc to call back. Worried mommy....