The symptoms that you are describing are usually associated with chemical exposure. I think the question to ask is what is the chemical involved and
who is releasing it and why are they releasing it.

Originally posted by ChaoticOrder
Here is a general summary of the 14 events suspected to fit the pattern so far (13 of which took place within the last month).
Barnett Stadium, Houston, Texas - 4th Nov 2011
- 23 spontanously ill and go to hospital
- HazMat team and firefighters called in
- same symptoms as other events
- suspected to be carbon monoxide poisoning
- air tests all come back negative
St. John Central High School, Belmont County, Ohio - 3rd Nov 2011
- 14 spontaneously ill and go to hospital
- emergency responders called in
- same symptoms as other events
- no idea what caused the event
- air tests all come back negative
Platte River Elementary School, Benzie County, Michigan - 2nd Nov 2011
- more than 100 ill in same day
- health officials called in
- same symptoms as other events
- suspected to be the Norovirus
- entire school disinfected
Joy Elementary School, Sioux City, Iowa - 2nd Nov 2011
- more than 85 ill in same day
- same symptoms as other events
- no idea what caused the event
- entire school disinfected
Gibbs High School, Knoxville, Tennessee - 1st Nov 2011
- 3 suddenly ill and go to hospital
- no idea what caused the event
- the whole event is blacked out
Alcott Elementary School, Hastings, Nebraska - 28th Oct 2011
- more than 80 ill in same day
- same symptoms as other events
- unofficially said to be Norovirus
- entire school disinfected
All Worth County Schools, Worth County, Missouri - 28th Oct 2011
- at least 260 ill in community
- same symptoms as other events
- cause is claimed to be Shigella
- entire schools disinfected
Pittsburgh Montessori School, Pittsburgh, Pennsylvania - 27th Oct 2011
- at least 157 ill in same day
- same symptoms as other events
- cause is claimed to be Norovirus
- entire school disinfected
Fairview Elementary School, Oconto County, Wisconsin - Oct 27 2011
- at least 23 ill within days
- same symptoms as other events
- no idea what caused the event
- entire school disinfected
Honea Path Elementary School, Anderson County, S. Carolina - Oct 27 2011
- at least 80 ill in same day
- same symptoms as other events
- cause is claimed to be Shigella
- entire school disinfected
Farmington High School, Dakota County, Minnesota - 15th Oct 2011
- at least 60 ill in same day
- same symptoms as other events
- no idea what caused the event
- entire cafeteria disinfected
Orange Unified Elementary Schools, Orange County, California - 12th Oct 2011
- at least 128 ill in same day
- same symptoms as other events
- suspected to be Norovirus
- entire buildings disinfected
Falcon Middle School, Colorado Springs, Colorado - 6th Oct 2011
- at least 160 ill in same day
- same symptoms as other events
- cause is claimed to be Norovirus
- school possibly disinfected
Beartooth Elementary School, Billings, Montana - 8th Sept
- around 230 ill in same day
- same symptoms as other events
- cause is claimed to be Norovirus
- entire school disinfected
EDIT: For those not following the thread and wondering why we now have 14 events, here are the updates I've made so far:
Update 1
Update 2