It's very unlikely shes egg bound. The average time frame for hens to start laying again after becoming broody and hatching is 4 to 6 weeks. Some hens will go through an entire molt after before they start laying again. Calcium suppliments aren't needed right now, as she's likely not ready for egg production again yet. The laying pellets surely was not what was causing the deaths, unless it was a bad batch of the specific brand or it was contaminated somehow. If they have mites, its likely the culprit, no matter if she has few or not. Even 1 mite or lice can make them miserable. Itching, potential for infections or bacteria contamination, etc. It already takes a toll on her being a momma (exhaustion, stress, etc), let alone mites sucking other stuff out of her. I don't imagine people would feel good in her situation either. I'm not familiar with mites to suggest much, but have you been treating the coop, run, yard, etc too. Just treating the chickens directly won't be enough. The extra vitamins, electrolytes, and suppliments can really benefit her right now.
