I'm having rather similar phenomena right now. Well mostly.
Goblins came. With their leader. Who happened to be former comic show employee.
So, I should have bewared his poisonous vapours. But I hadn't.
A dozen of dwarves got contaminated by his excretions. The syndrome causes either paralysis or function impairment onto spine. (Seen spines painted in blue on contaminated animals.)
Now I have five infinitely winded dwarves sealed in my courtyard along with severely mangled goblin overlord, who for some reason doesn't attempt to attack them.
I've managed to bring another six or so to hospital. But the doctors don't seem to attempt to diagnose them. Actually, some of them probably had been diagnosed and that caused them to suffocate.
They don't have any contaminants on themselves but their clothes are soaked with extract. I've tried pumping and pouring water on them, that failed to remove contaminants from their clothes and didn't give water coverings to them. Their happiness is seemengly locked, I have a couple of fine, one ecstatic and one miserable dwarf, this hasn't changed for two seasons now.
Interestingly though, when I deconstruct the bed under such dwarfs, they give error message "cancels rest: interrupted by goblin overlord" which is followed by doctor's "cancels diagnose: patient not resting".
The overlord himself behaves oddly as well, the siege is long broken but he didn't seem to attempt retreat. As mentioned before, all his appendages are mangled, but he doesn't even attempt to push the comatose dwarfs near him. All he does is eventual additional sprinkle of secretions.
Later on, several animals and one dwarf, that didn't participate in the fighting, have died regularly after contacting the secretion pools on the floor.