bottle fed bunny

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?

I have never bottle fed bunnies, but have bottle raised a lot of kittens. If that was a kitten, I'd say she is weak, and probably right on the edge of a respiratory illness, and treat accordingly. When kittens pant after they eat, it's because they are weak, and it is hard for them to nurse and breathe and keep up with both, it takes too much energy.

Best of luck to your bunny! Hopefully someone who knows bunnies has more info!!