I have 4 domestic bunnies that I had to bottle feed over the last 2 weeks. They are roughly 2 weeks 4 days old. All are eating well and I started introducing some greens. When I started, there was one that was always a bit smaller. She is eating ok, but after bottle feeding her, she pants. Today was the first day she has been holding her head up after feeding and seems to have a crackle sound that is very faint. Any ideas on what I can do for her or what it might be?