From what you are describing, I would be suspicious that he has sour crop. Do a search on BYC about it, there are a lot of threads on it.
If the crop is soft and extended (you don't have an impaction) it is usually caused by a bacterial imbalance in the crop and it takes time to reestablish the...
http://www.feathersite.com/Poultry/CGK/Lakens/BRKLakenvelder.html
That is the Feathersite page for lakenvelders.
That chick has a single comb doesn't it? Wyandottes (hopefully) rose comb, and the black on his neck seems to be coming in pretty solid.
With the chest, is it doing anything...