Please help, any advice appreciated

Any advice appreciated, I don't know what to do anymore

My rats Yuki and Rue passed away suddenly from respiratory infections last week. All of my other girls are now on antibiotics. When I took Rue to the vet, I also took in all of my other girls. They were all checked and none of them had congestion or any signs of a respiratory infection but they were all prescribed antibiotics. My girl Poppy has been declining, even with the antibiotics and nebulizer treatments. We're 6 days in to the antibiotics and Poppy is starting to heavy breathe like her sisters did right before they passed. I don't know what to do, I spent a little over $1500 on vet bills just this past week and I can't afford to keep doing that. Her vet wants me to come back in but the one I go to is an hour away from me and extremely expensive. I don't know why my girls have been showing no signs and then they rapidly decline. I don't know what I'm doing wrong. After my other girls passed, I cleaned every item they have with a bleach and water mixture to completely disinfect everything. I have an air purifier next to their cage. They have a clean diet of oxbow adult rat food and fresh fruits and vegetables. They don't have any bedding because any bedding I've tried has always made them sneeze so I just use fabric and clean it every week with unscented laundry detergent and baking soda. I feel like I'm doing everything right and they keep dying and I don't know why. I'm extremely stressed about it and their deaths have really traumatized me. I don't know what I can be doing better. Please help.

**Edit to say I brought them all in to the vet 6 days ago and Poppy just started heavy breathing today after 6 days on antibiotics.

Any advice appreciated, I don't know what to do anymore

My rats Yuki and Rue passed away suddenly from respiratory infections last week. All of my other girls are now on antibiotics. When I took Rue to the vet, I also took in all of my other girls. They were all checked and none of them had congestion or any signs of a respiratory infection but they were all prescribed antibiotics. My girl Poppy has been declining, even with the antibiotics and nebulizer treatments. We're 6 days in to the antibiotics and Poppy is starting to heavy breathe like her sisters did right before they passed. I don't know what to do, I spent a little over $1500 on vet bills just this past week and I can't afford to keep doing that. Her vet wants me to come back in but the one I go to is an hour away from me and extremely expensive. I don't know why my girls have been showing no signs and then they rapidly decline. I don't know what I'm doing wrong. After my other girls passed, I cleaned every item they have with a bleach and water mixture to completely disinfect everything. I have an air purifier next to their cage. They have a clean diet of oxbow adult rat food and fresh fruits and vegetables. They don't have any bedding because any bedding I've tried has always made them sneeze so I just use fabric and clean it every week with unscented laundry detergent and baking soda. I feel like I'm doing everything right and they keep dying and I don't know why. I'm extremely stressed about it and their deaths have really traumatized me. I don't know what I can be doing better. Please help.

**Edit to say I brought them all in to the vet 6 days ago and Poppy just started heavy breathing today after 6 days on antibiotics.