also, try to make sure you have a few peices of thread forbidden for moods, a weaver will automatically gather it all up and turn it into cloth if you dont watch out. if you want to stop that, you can lock the looms up, disable the jobs in the dwarves, or there is a setting somewhere in the mess of menus the game has to turn off this automatic behaviour. this has driven me crazy before, having a dwarf demanding thread, and then trying to figure out where all my thread went.
in an emergency like this, as aquizzar said, you can get the thread easily either from cave spiders, unprocessed pig tails or rope reed in your food stockpile and from the human and dwarven caravans. if there is no prospect of that then wall him in, so he doesn't go mental and kill someone important.
you get the little spiders with some underground features, like cave river or pond. unless i have them i tend to request all my cloth and thread from the traders, as i find the plant route tedious.
also, the wiki has an invaluable list of fey mood demands and their meanings along with other useful strange mood advice here, url]http://www.dwarffortresswiki.net/index.php/Fey_mood#Demands[/url] although if you want it really interesting then avoid reading it and try and figure out all the cryptic drawings and mutterings as you play. i had a little list on paper next to my pc as i didnt find the wiki for the first year or so i played this game.