How to get antibiotics into a sick rat?

One of my rats is quite ill, and she was a rescue rat so has never come to trust humans...when I try just inserting the syringe into her mouth and , she doesnt seem to swallow and the liquid runs out of her mouth. I tried putting it on yoghurt which she likes but she wasnt falling for that either. I have four other rats, so putting it in the water bottle might not be the best idea. Does anyone have any other ideas about getting the baytril into her?