sounds like tyzzers disease
http://www.gerbils.pwp.blueyonder.co...ls/tyzzers.htm

Antibiotic treatment of infected animals has yielded variable results. A number of studies have examined various antibiotics for treatment of Tyzzer's disease. Although techniques and evaluation methods varied, tetracycline, oxytetracycline, and penicillin were the most effective antibiotics for alleviation of clinical signs due to C. piliforme infection.
You can get most of these at the pet store labeled wet tail treatment or labeled as other gerbil antibiotics.

If it is this, make sure you clean everything:It is important to remember that whilst Tyzzer's disease is a common cause of illness in rodents there are other conditions like Listeria, Salmonella and E. coli which can also cause serious illness and death. In many cases the symptoms of these can be similar and they should be dealt with in a similar way. These diseases have an important difference from Tyzzer's disease. All of them are potentially very dangerous for humans and can be fatal to young, ill or elderly people. For this reason no illness of rodents should be treated in a cavalier way. If disease appears it is important to review husbandry practices, treat infected animals if appropriate and to ensure that all sources of illness are destroyed or sterilised.