No eggs for 7+ weeks....?

Hi there We are pretty new to chickens, only had them for 2 1/2 months now! Our first 6 girls where 5 weeks old when I got them, but our dog broke into the pen and played rag doll with them all the 5th day we had them ( fixed that from happening again! reinforce our gate) The next day we received 2 hens in condolence from a friend, golden sexlinks girls, both 1.5 years old, great layers! I also broke down and bought 4 chicks: 2 silver laced wyandottes and 2 golden laced wyndottes.

So my concern: a week before I put the new girls(the 4 wyandottes girls) outside with the big hens, both hens stopped laying. Sophia looked (and still looks) like she started her molt. Rose on the other hand just started to get sluggish. 6 weeks ago my 3 year old daughter found Rose dead in the corner of the run. She was just laying there like she was asleep, but when I picked her up, water (or some kind of liquid) poured out of her beak...? (later talked to a friend who confirmed her death: Egg-bound ) The new girls didn't seemed fazed at all. But Sophia has been a royal pain in the butt ever since. She is mean, squawks at everyone and everything, still hasn't laid an egg, and still looks like a molting hen.

Any suggestions would be awesome... Just want a healthy bunch of girls for the family and I to enjoy

Oh, and No mites.