Batch of chicks not growing

My nyd chicks havent grown the only ones. Growing are three in a different bin. My others are with bantams that i got recently. Can worms stunt the growth if they have worms? What else can cause them to not grow. Even the bantams arent growing.

 

Possibly from the two bantams i got from someone whos birds apparently were sick. I got a adult bantam hen that had bad scaly leg mites she came with 5 chicks only two are still alive. From the same person.

 

I already treated the hen with invermectin shes looks about 90% better. She wasnt in with the two smaller bantams they had them in seperate bins when I got them. The last two chicks that was with the hen are in with my seramas. I already treated them aswell. Im feeding them dumor chick grower but is for game birds could that be the reason? Plus ive been giving them medicated chick starter.

 

Apparently my bag doesnt say game birds but doesnt list chickens on it saids turkeys,chukar,etc it has 24% protein its the same feed i was giving my seramas when they were chicks.