I have had 2 chicks that I call “cry babies”. They cried all the time and was always running up under the other chicks and acted cold all the time. And they were also much smaller that the others. I lost one at 8 weeks (when I thought all was going great) and one at 4 weeks. I don’t know if it was something neurological or what was going on. That was my experience with mine and I know it was no fault of my own. I am still a fairly new chicken owner, 18 months. Hopefully yours will be fine, I just wanted you to know you are not alone.