Help!

I have had my babes for about one week. I ordered 6 of them from My pet chicken. When they arrived i opened the box to find one of my buff orpington very sick... pretty much deadthen about three days later i came home to check on them and tilly my other buff orpington half dead. now with only four outta six girls left Nugget is having diarrhea and seems less active then the others! she is a wonderfull little chick and i couldn't bear to loose her!!!!
Please help!
Any suggestions would be awesome