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
So, everyone in America just assumed a two-term limit already - but FDR, riding high on public opinion and the sort of this is a new era, and old rules are no longer appropriate sentiment that characterized his entire policy, decided that a third, and even fourth term were a good idea.