The thing that I was immediately concerned about, and your post supports my concern, is the possibility of botulism. I was "fishing" for information that might have pointed towards him getting into something like a mucky spot that might have maggots or droppings or soured feed, etc. And the area under the pens sounds like that type of place.
The off balance concerns me.
I would consider giving him a bit of a flush just in case something he ate was either toxic or could have been carrying botulism. I would make it a very light flush, not a hard one, because the cause is really still not known.
I've used a molasses flush on ducks before and it worked well. With any flush, you should also give electrolytes in the water to counteract against dehydration. The flush literally flushes out their digestive tract, so you will want to get him to eat pellets/crumbles that you wet. They are a lot more likely to eat their wetted pellets than dry when they don't feel well.
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Molasses Flush:
1 cup Molasses
2 ½ gallons water
5 6 grams Durvet vitamin and electrolyte powder * Optional
Use as a flock flush when you cannot administer flush directly to each individual bird.
! Do not exceed 8 hours ! ! After 8 hours replace Molasses flush with vitamin and electrolyte water !
Or this:
Activated Charcoal Slurry
1 tsp. Activated Charcoal Powder
½ tsp. Psyllium Seed Husks or Flax Seed Meal
8 oz. Pure Water
Or try:
1 tsp. Activated Charcoal Powder
8 oz. Pure Water
Dose 6 8 times daily
If you are administering ANY Drug or drugs to you poultry, or if they are drinking Oxygenating Water, please wait at least 1 hr., before you give them the Charcoal Slurry. This will ensure that the Activated Charcoal will not inadvertently absorb or otherwise adversely affect your other treatments.
These flushes will cause slight to moderate dehydration as they work to expel toxins and foreign matter from you fowls system. It is important to use care when administering flushes. Be sure to monitor your fowl before, during, and after the administration of a flush. After flushing, offer a steady supply of vitamin and electrolyte fortified water until a full recovery is made.
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