Easter Egger/Fryer Mix not holder her head up properly

[Newbie80]

I have, what was told to me to be an Easter Egger/Fryer mix (she looks like a fryer and lays blue eggs so they are probably right). I hatched her from an egg last May (it is not November). We also have two of the smaller breeds of New England chickens - they were hatched in July. Yesterday we introduced two full grown chickens - one Plymith Rock and one rusty brown (sorry can't remember the breed). Today my Easter Egger is not holding her head up properly, like she's exhausted. Sje looks like an exhausted child who is trying to stay away - you know the bobblehead. There aren't any new cuts on her (she has an old cut from last week on her beak - we don't know what from since she gets along with the two NE birds). She drinks a bit but isn't eating much. She doesn't make any weird breathing noises - her breathing seems normal. No crusty eyes.
Any thoughts?
We really need to prepare my daughter if she Beth (the chicken) is going to pass. My daughter raised her and cared for her since Beth hatched and it would break her heart. It is breaking her heart right now.

Thanks

 

[Eggcessive]

Some guesses on what is wrong with her are coccidiosis, mites, or worms. The symptoms of coccidiosis are lethargy, poor appetite, sitting fluffed up in a ball with neck pulled in, ruffled feathers, and diarrhea. In some strains there can be blood in the stools. When adding new chickens sometimes new strains (there are 9) of cocci brought in, some that your older chickens might not be immune to already. Corid (amprollium) is the treatment for 5-7 days. Some mites only come out at night, so checking her vent area for mites and eggs, may be necessary at night with a flashlight. Valbzen and Safe-guard liquid goat wormer are good to use for worming. Also, check her crop (especially in morning) to see that it is emptying--sour crop or impaction would make her sick.