It's been 86f here for the last couple days, (warmer than the 65-75 it has been) and my one year old 7egg/week EE Betty hasn't laid in two days and is suddenly acting very lethargic. All my other birds are under 5 months and panting but quite spry. Her comb is still red and she will drink, but she is slightly fluffed up and just hanging out under the dense bushes, low appetite (even for tomatoes).
I thought maybe she had become a bit broody because she has been on the nest a lot since our Elenore started laying a week ago, so I put her in the nest box after ensuring it was cool and well vented but she left immediatly post haste. (Side note: Betty was walking around the pen outside the coop yelling like she was laying a crazy big egg for about 20 minutes after Elenore's first egg, kind of funny. Betty had already laid that day and has never made a fuss about laying large eggs anyway.)
Edit to add: Well still no egg, but after the temp dropped below 80f this evening she perked up quite a bit and started eating more. I didn't feel any egg lump in her belly either, so I think it's just the stress from the sudden rise in heat over the last few days.(not that 85 is super hot but we are acclimated to 60s and low 70s)