Wyandotte "gold & silver laced"

[Iaseye]

Hi there! I have an unanswered mystery that nobody I have asked or even the feed store could answer.
I am a brand new chicken mom, picked out an assortment of chickens at 1 day old the end of February. For the next month I struggled with the wyandotte breed both silver and golden laced dying on day 2-4. I live in Northern California so the qeather isnt bad at all.
Everytime one would die I'd run back to the feed store and grab a new baby coming from the same place. On the 3rd week it was a new batch of chicks they received. STILL the wyandottes died... all the other breeds of chicken lived no issues. Everytime I went back to the feed store I ended up bringing back a new breed as well as the wyandotte, because chicken math! Haha
Anyways I was wondering if anyone had any idea what the heck happened? I kept them with a heat lamp, big tote in my living room, medicated feed, fresh water, pine shaving bedding. I watched them like a hawk! I have no wyandottes, I do have 8 other breeds of chicken tho and are all 9 and 7 weeks old now.
It just really bothers me that I couldn't help the wyandotte chicks live. Any ideas or thoughts would be wonderful. Thanks!

 

[All4Eggz]

Wyandotte’s are very cold hardy so they do best in colder weather. They are not as heat hardy so that could’ve been the case.

 

[Iaseye]

Wyandotte’s are very cold hardy so they do best in colder weather. They are not as heat hardy so that could’ve been the case.

Hmm, I wonder

 

[3KillerBs]

Sounds like bad stock from the source.

Heat/cold tolerance shows more in older birds than in baby chicks.