I don't know if this is her first heat or not. She had a slight fever yesterday and she wouldn't eat or drink anything, and when she tried she puked it back up. She didn't even have the energy to stand up to come to me when I called her from 5 ft away. I just lost a kitten yesterday, so I might just be freaking out, but I don't know. Please help

Is the dog drinking ? You should take the dog to the vet NOW.

Take it to the vet ASAP!

When in doubt the vet is always your best bet.

A dog in heat isn't lethargic, at least not to the point that they have no energy to come when called from 5 feet away.

Better safe than sorry. Go to the vet.