So I recently purchased 3 med female rats and 1 male from a pet store to start my breeding project. On day 1 I noticed one was sneezing. I read up a little and thought it was common when using aspen. Well a few days later one female got a hunched back, started gasping for air and acting lethargic. I immediately fed her off to stop her suffering. 2 days later female #2 exhibited sunken sides walking completely hunched and slow with half closed eyes. The male started acting like female #1 hunched back, gasping for air and lethargic. I fed them both off. I bleached everything and gave female#3 a new tub. She has been sneezing a lot but her coat appears fine, she walks fine doesn't exhibit any other signs other than sneezing. I purchased another male after a few days of watching her I placed them together. The pair now seem to be fine other than the female sneezing. Will she likely get sick like the others or do you think I fed off the problem? I have changed bedding and bleach multiple time in the last few days. Thanks.