When our pup was healing from a jaw injury, she had a taped muzzle on for the first few weeks, and she was fed via tube. Her original weight when we took her in was 18lbs at 9 weeks. In two weeks she was down to 14lbs, which doesn’t seem like a big loss, except she was growing as well. You could see her hip bones and ribs. Per vet, we gave smaller meals more frequently throughout the day. When she was switched from a tape muzzle to a regular muzzle that allowed her to open he mouth enough to lap food, we would blend her food with water until it was a soft serve consistency. You may want to try that if she’s low on energy and not up for chewing kibble. Or just soak the kibble in a bit of warm water to soften. Quality kibble 6-8 times a day, and when the muzzle finally came off, she right on track for her weight. Now at 6 months she weighs 51lbs. Slow and steady wins the race here. You don’t want to start offering high fat items or overfeed, it could be just as dangerous as underfeeding. So feed her the recommended amount in smaller portions more frequently. At least, that’s what worked for us. Hope you get more answers soon!