2wk old barred rock with swollen vent, will not eat. Please help!!!

Have 6 week and half old baby chicks. Three barred rocks and three rhode island reds. One of the barred rocks had trouble passing a few days after she arrived. I dipped her in warm water and dried her off and she seemed fine until yesterday. Her vent is now very swollen. I tried the warm water and applied some gentle pressure and she passed quite a bit, but she is still swollen, won't eat and drinks very little water. I am giving her one drop of olive oil every hour and I don't know what else to do. She is just standing around not enteracting with the others now. I am so worried and so in need of advice. Can anyone help?