Other causes of nausea include side effects from medications, pain, pregnancy and morning sickness, seasickness, viral infection, alcohol toxicity, and disease of the brain, esophagus, stomach, gallbladder, liver, pancreas, and intestine.
so roosevelt was able to win more than two terms because there was not yet a formal term limit on the presidency and the unique conditions when he ran for his third and fourth terms made his arguments for breaking with tradition acceptable to a majority of american voters
The restriction you mention of a president only being allowed to serve two terms was the 22nd amendment to the US constitution. It was ratified in 1951, six years after FDR left office. (FDR served from 1933-1945). You can see more about the 22nd amendment here: http://en.wikipedia.org/wiki/Twenty-seco...