I went out to give more food and water to the little chickens. I picked up one Dom to check the injury on her leg and saw that she had a really big lump high up on her chest. I know that's where the crop is, so I'm kind of panicking thinking maybe the chicks all have Marek's or impacted crops! Every chick I checked has a squishy lump (some bigger than others), but I made sure each one of them has been defecating regularly. Any idea what it could be? Do they need more grit? There is a dust/chick grit box in the coop and I'm wondering if that grit has been too small. Did I screw up my chicks?