@MamaChick74
Crop issues can be a symptoms of worm or cocci overload and sometimes reproduction disorders as well. Here's more info on crop issues - I recommend that you read the entire article, excellent descriptions and treatment options...
I agree with @PD-Riverman it would be a good idea to worm them.
About your food - how much scratch are you giving daily - is your pellet food layer feed?
Worms can cause some of the weight loss you are seeing, but you need to evaluate your feeding as well. Most layer feeds are fairly low in...