Green’s Dictionary of Slang

doodah n.¹

an emotional crisis, a nervous, tense state.

1940		Wodehouse Eggs, Beans & Crumpets ((1951)) 74: But the thought that the hour of that springing [i.e. of bad news] must inevitably come kept him in pretty much of a doodah.
1949		Wodehouse Mating Season 221: That’ll give you a rough idea of the sort of doodah I’m in.

In phrases

all of a doodah (also all of a doo-da)

in a fluster, in a state, very agitated.

1915		H. Rosher With the Flying Squadron (1916) 97: I had lunch with the Rs and five daughters (swish, I was all of a doo-da!) and then spent the whole of the afternoon trying to get my beastly engine to go.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 5: All of a Doodah: An expression used of an aeroplane pilot getting nervous in mid air (Air Force). Pre-War ordinary slang.
1929		J.B. Priestley Good Companions 309: I don’t care if a man’s been fifty years in the business, there’s still the same old thrill comes back. Opening night – all of a doodah!
1932		D.L. Sayers Have His Carcase 242: My dear, what’s happened? You’re all of a doodah!
1937		E. Garnett Family from One End Street 135: ‘I feels all of a do-da!’ exclaimed Mr Ruggles.
1944		J. Maclaren-Ross ‘Gas’ in Bitten by the Tarantula (2005) 163: Well, we were all of a doodah [...] all rushing to and fro.
1952		Wodehouse Pigs have Wings 28: Poor old Clarence was patently all of a doodah.
1960		Wodehouse Jeeves in the Offing 41: When Upjohn came out just now, he was all of a doodah.