I'm sorry you're having trouble.
Since you have 4 month olds, I would use the SS Flock Balancer 20% Booster feed. You can feed that to all ages, provide oyster shell free choice for the laying hens.
Once the 4 month olds comes into lay, then you can transition to egg layer.
I buy their Traditions Egg Layer Feed, but I also use the Flock Balancer as well. Since I have roosters, I usually do 1/4-1/2 layer mixed with Balancer, it just depends. For youngsters, broodies, etc. I give only Balancer.
All grain (5 grain scratch?) isn't a complete feed so providing a nutritionally balanced feed *should* get you back on track.
I understand, the Flock Balancer is more expensive, but I think you should be fine with the Layer feed once all your birds are laying.
For a lethargic bird - it really depends on the cause. If you can be a bit more specific with symptoms we may be able to offer suggestions.
For a "quick" pick me up when I just don't know what is wrong, I would use Poultry Cell. General direct dose is 1cc per 3 pounds of weight. If you are talking for a chick depending on age then 2-3 drops twice a day.