Three Rats Sick at Once

Question
Three of my rats came down with the same symptoms of illness on Tuesday... two at the same time and one a day later.  These included, lethargy, puffed up coat, increased porphyrin, inability to move and lack of balance, frequent urination and they stopped eating and drinking.

One has already passed away, the second seems to be improving slightly in that she can now move around.  But she's still puffed up and breathing badly.  This morning the third girl to show symptoms is now not moving at all, can't eat, etc and just appears to be going downhill.  

Vets have these last two on Baytril/Doxy with nebulising twice a day.  But with this last girl doing so badly since last night, I'm at a loss, it's the weekend with no emergency / after hours vets to assist and I don't know what to do with her :(

The vets also can't tell me what's causing this and I have three other rats I'm very concerned about.

Answer
Its probably Streptococcus pneumoniae(pneumococcus) which is a very nasty and very contagious infection that can cause death anywhere between 12 and 24 hrs.  The rats are not being treated aggressive enough. They need put in the hospital and given gentocin via injection for five to seven days. The benefits outweigh the risks. This needs done right now in order for the rats to recover.