Yes, that's correct. You will stir the mixture a couple times a day. This keeps the "scoby" (the white stuff that forms on the surface, which is NOT mold) mixed in evenly. You can cover it, but leave the lid slightly offset so air can circulate and gasses can escape.
How many chickens in your flock? I have fifteen. I use two plastic buckets I bought from the hardware store for a couple bucks each. I ferment enough Flock raiser crumbles at a time that I feed out over about three days, keeping the buckets indoors. The fermented feed begins to lose it's potency...
The fermented feed process is very simple and easy. I've been fermenting for sixteen years and never had any problem with mold.
There are many different kinds of mold, and not all are bad and dangerous. The ones that colonize fermented feed exist in the air all around us. Those are the good...
I see no harm in doing that vitamin therapy. Do you do fermented feed? My flock carries an avian virus (LL) and fermenting makes more of the vitamins and nutrients in feed available, boosting the health and immune systems of the flock. Over the years, I believe this has helped reduce the number...
If the lameness was due to the pressure of an egg, getting the egg out will resolve it.
I didn't mean to alarm you with the possibility of another virus. Lymphoid leucosis (LL) is even more common in flocks than Marek's. Lameness is usually one of the first signs, and first symptoms show up...
It may not be Marek's, but LL can cause these symptoms at exactly this age. It goes against our innate sense of fairness, but a flock can carry both viruses.
But always treat for vitamin deficiency when lameness crops up since that's very common.
Giving calcium is always a safe move if a stuck egg is suspected.
And by the way, I am one of the few who recommends NOT sticking fingers into the cloaca to try to feel for an egg. Most of the time a stuck egg is in the oviduct where it can't be felt. If the egg is in the cloaca, you will...
Marek's symptoms can come on suddenly. But the symptoms can be from heat stress if you suddenly had a hot day following a cool stretch. Mold exposure and petroleum distillates exposure can also cause these symptoms. See anything there that fits better than the others?