It is too bad you didn't know that chickens were intolerant of high heat. They can take very cold conditions but heat will kill them.
Even heat tolerant breeds like Mediterranean, Cubalayas and Fayoumis still like 60-70F better than temps around 100.
It ranges from -20F here to 110F - I've lost birds to heat but never to cold.
It is too bad you didn't know chickens need fresh water every day. I read in one of your posts that your birds had gone over a day without water in the past and they were OK. They weren't OK, they lived.
When poultry are overcome by heat, especially when dehydrated, they need to be taken somewhere cool.
They need to be taken into a basement or air conditioned space. And not just till they look better, they need to be in that space at least 3 days. Heat effect is cumulative. If you take a bird that has recovered back into 100F, it could still die.
I think the 4 died either yesterday or Saturday, it stinks.

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That tells me you didn't even check on the birds all weekend.
we had temps over 100 here for a few days, unless its the lack of food/water for 2 days that did it im concerned its more than that, lost another 1 lastnight that was really weak

what can I do? I am concerned I switched from chick feed to layer feed too early and they arent getting the nutrients they need ...
A combination of the two, heat and dehydration.
While chickens should have food available all day, they can survive a day or even two without food.
However, under no circumstances can they go 24 hours without water. Even in winter they need to be able to drink more than once a day but in summer, it is critical.
If I am struggling to get them to eat or drink how else can I get the corid in their system? dropper like ive been doing?
I'm going to diverge from the advice of others. I would not dose with Corid. A 20 week old flock of chickens that have been out foraging will not all die over the course of a couple days from coccidiosis.
In fact, I would be surprised if one bird could die from coccidiosis given that situation.
Your birds don't have any disease so you can quit worrying about that.
Your birds died from being without water in hundred degree heat. It is as simple as that.
Edited to correct age of flock.
