My fish has lying on the bottom but still eating, she looks like she has enlarged around the bottom of her stomach but I'm unsure how to tell if she is pregnant.
If she is gravid (pregnant), she isn't very far along.
If fish are acting unusual, do a 75% water change and gravel clean the substrate every day for a week. See if it helps.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.