... didn't know what was wrong with him. She gave us an antibiotic for us to give him. He is reponding to food but hardly eating anything. We have managed to give him the antibiotic and some water via the syringe. He is naturally smaller than his brother but has got skinnier over the last couple of days. His heartbeat is noticeably lower (can tell just by looking at him) than his brother. He has made the effort to move from one side of the bottom tank to the other and got settled with the other gerbil however he looks like he is breathing heavily. Any idea what is wrong with him, and more importantly, what we can do to help him?