Lead singer John Sebastian wrote this song, where he sings about getting sick in Savannah (after eating cream and bananas on a hot day - not a good idea). The remedy is jug band music, which as the doctor points out, makes him feel just fine.
Sebastian cops to stealing many song ideas from the "jug band masters of Memphis, Tennessee." On his Welcome Back concert DVD, he explained: "This tune didn't come from Memphis, Tennesse, it came from New York City. It's sort of a disturbed tune, you see. People think I write all positive songs - this is not true.
In 1964, before forming The Lovin' Spoonful, John Sebastian and Zal Yanovsky were in a group called The Mugwumps along with Cass Elliot and Denny Doherty, who later formed The Mamas & the Papas. When this song was released on the Daydream album, the Mugwumps were only a memory, but a cover version was released as a single on Sidewalk records by a completely different group called the Mugwumps. This was clearly a bit of misdirection, and it worked: the single bubbled under at #127 on the Hot 100.