My girls pick on each other all the time, it's really no big deal. It would probably be helpful to get a third girl so the aggression is spaced out a bit between all of them.

As for her labored breathing, I would think she's getting a respiratory infection. Are her eyes and nose porphy(red stained)? If she's thin, get her separated and if you have some canned, high quality cat food or something, give her that. Ensure works well too, just anything without lactose. Canned tuna is good for protein.

Do you regularly bring in unquarantined rats to feed Zeke? If so, that may be the source of her problems as those rats bring in god knows what, and it takes about a week for the symptoms to manifest themselves.

If you have a 10-gallon with a lid, and a water bottle that hangs on the side, put her in that. Add a heating pad(on low) under about 1/3 of it in case she's cold. Taking her into a hot steamy bathroom would help break up the crap in her lungs and let her breathe better.

I have 22 rats, hence why I feed mice from my own breeding group. Nothing icky comes in that the rats are susceptible to(mice are quarantined anyway, regardless). Pet store rats can carry alot of things such as Streptococcus(about 7 of my rats died in about a week's time following an outbreak of strep-based pneumonia), internal/external parasites, and other bad bacteria that our pet rats haven't built up an immunity to.

If you MUST feed rats to Zeke and have pet rats at the same time, keep them at a totally different end of the house. After you bring the rat-to-feed home and it is fed off(you go NOWHERE near your rats), you need to sterilize your shoes, wash your clothes and take a shower.

Blowing your nose is especially important. This is the only way I know of to prevent unwanted illnesses coming into a healthy house of rats. I practice this everytime I go to a pet store(as even those Strep carrying baby rats came from Petsmart...).

Keep her warm, hydrated and eating(meat babyfoods, ensure, sugar water) until you can get her to the vet on Monday.