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
FDR was able to get the nomination four times and was elected four times. He won his first election because the country was in a depression and the Republicans had been in office for 12 years. Roosevelt promised a New Deal and with the help of a supportive Congress got sweeping new program into law.