My layer crumbles are 16%. Never heard of 12% layer, that seems very low, to me. I'd increase protein immediately. It take a lot of protein to lay eggs, or grow feathers. I'd give at least 16%, and add a scoop of dry dog or cat food, or a little 20% for a boost. Add oyster shell or feed their own eggshells back to them for calcium and minerals.
I don't know how much protein sweet feed has, and since it's for horses and cattle, it may have salt added. Some feeds for horses and cattle aren't very good for poultry. Some of it they won't even eat.
Are you sure they're molting again? Feather loss could be due to a heavy mite infestation, which would also cause a drop in egg production.
Or maybe only part of the flock molted before, now the rest are starting. They don't always molt in unison. Mine sure don't.