I'm sorry you're all having to deal with this. The baby issues are hard in and of themselves, but to have the medical system not listen and dismiss your concerns can make it even more disheartening.
We had a similar spate of ERs dismissing us with our little guy when we were trying to get him treated for jaundice. They kept sending us back home and waiting because the numbers were all over the place due to different ways they took blood draws at each place. Eventually I refused to leave the ER until he was admitted. By that point it was our 3rd day back at the ER for the same dance and i was over it.
Hang in there and give the little one extra cuddles. Feel free to reach out if you'd like to chat or vent anytime.