Like the others said, probably cave adaption, or one of the MASTERWORK diseases. If the fort is old, and you've kept everyone inside for a while, cave adaption. If it's new, or doesn't seem to be because of the sun, probably a disease, and should run through the fort after a bit.
If it is one of the diseases you'll want to try and figure out who the carrier is if you are going to have more immigrants, unless you don't mind any new dwarves getting sick and painting your floors green for a few months until they are immune like the rest.
The puking disease isn't all that bad really. The last time I ran into one it was year 1, and the disease put all of my dwarves to sleep before I could set up any real defenses. They didn't seem to enjoy waking up to half the fort dead from a few thieves and some wildlife...