Cochin Hen that was laying 3 to 5 eggs a week, suddenly QUIT! Why?

[lindabean]

I've had this hen about 4 months. She was said to be less than a year old when I bought her in May, and she has been laying nice big brown eggs since she got here. Then suddenly, she quit laying, about 10 days ago. That was a day or so after I put Oyster shell in the pen for the first time. She wasn't getting off the nest hardly at all for the first 4 days or so, but now she gets out alot more, but still spends a lot of time either sitting on one of the other hens eggs or on an empty nest. The last few days she has been out & about, eating well, drinking water (with about 1T ACV per gallon). The only thing I can add is that it has hit 100 almost every day for the last week, although their pen is in the shade of a huge oak tree and I've given them all water to wade in, using large potted plant saucers. They also have additional shade under their hen house. Also, the first day I put out the Oyster shell, it all disappeared. I put it on the ground, so it could have been scratched in. Since then, I put a small dog crate bowl attached to the side of the pen, so they can't get in and scratch in it, or spread it around.
So should I be worried about her? These are the first hens I've actually harvested eggs from, so I really don't know what I'm doing here. Last flock was over 20 years ago & they were afternoon entertainment (I guess they laid their eggs at the neighbors coop as I never found eggs around my place. I was in a small rural town, & our chickens visited around the neighborhood.)
I also have a Rhode Island Red hen that is supposed to be about 5 or 6 months old now, and she seems happy to just eat & poop. I keep telling hubby we just need to be patient (but I secretly give her pep talks mixed in with a few threats, although I don't think I could really EAT her.

) They are all eating Layena crumbles.
Hope somebody has a suggestion. I don't think my vet treats chickens so I don't know what I would do if she needed help.

 

[ranchhand]

It may well be the heat, but it sounds like she might be trying to go broody as well. I know mine lay a lot less when it gets hot, but you're doing all the right things. Maybe just wait a while and see what happens. My bantam cochins only lay every other day, whereas they started out daily.

Show the RIR the oven and tell her to get busy!

That may be the heat too. Or she may be a late bloomer!

BTW you have my sympathies for the heat- I lived in the Hill Country for over 20 years, and those summers are brutal!