Female guinea acting funny

Could be either, is she eating and drinking as usual? Is she interested in treats? Have you noticed if she has diarrhea or a wet vent area? My Hens sometimes act a little weird when they are starting to lay, so that could be it... or she may have a nest started already and she doesn't want to wander too far from it now, so maybe watch her and look around where she tends to linger.

Good luck, hope she's fine

I've never had, or even heard of Guineas coming down with Merek's so I can't say that's what's wrong with your Hen. With a mixed flock I guess it's possible tho. A vet would have to diagnose it to confirm it for sure, but that can be costly.

I'd definitely separate her, give her water with electrolytes and vitamins in it and try offering her some meal worms to get some protein in her, along with her regular diet, and see if she's eating. Keep her warm, (but not too warm) especially at night. If she's not eating she doesn't have the energy to keep herself warm...

Wish I could offer you more advice... good luck with her

Some Guineas just fail to thrive, for whatever reason. Usually genetics or systemic issues due to incubation problems, too much inbreeding within the flock, un-hearty/poor breeding stock etc etc. There's a lot of things that can/will cause failure to thrive, sometime's it's impossible to narrow it down. If she's always been "off", then I'd guess that her "defects" have possibly reached their peak, and are finally taking her down. Sorry in advance if you lose her :( I think it's a good idea to isolate her from the rest of your birds, just in case she does have something contagious tho.

Nature space.

She could also be egg bound if she is laying. All that PeepCA is correct. I usually wrap them in a towel to calm them when handling them. If they are from outside. Water and electrolytes are very inmortant! I usually mix their Wild Game crumble with warm water to a smooth consistency leaning on the side of watery. They seem to like this esp. when ill.  Check her every few hours to see her behavior. I also make sure they have plenty of Oyster shell around for the missing calcium. Had one act as you are saying and she laid an egg 2 hours later with no shell., just membrane. It still took her a couple of days on her own to act strong enough to go back out with the others.  

Good luck with her. Let us know what happens.

Daylily

Feel/palpate her lower abdomen area, you may be able to feel the egg if she is egg bound. There will be an obvious lump, don't squeeze too hard you don't wan to break the egg if you feel one. If she was egg bound and it burst, she'd be leaking and have a wet vent area. And yes they can die from it, if infection sets in,which is common from a burst egg. You can do a search in the Chicken forum here on BYC for egg bound symptoms ans possible treatments.