The definitive history of Hitler is found in the superlative two volumes by Kershaw I. Hitler 1889–1936: Hubris and Hitler 1936-1945: Nemesis. Penguin Books; 2010.
The best books on Hitler’s medical history are by Redlich F. Hitler: Diagnosis of a Destructive Prophet. Oxford University Press; 1998; and, Eberle H, Neumann H. Was Hitler Ill? A Final Diagnosis. Polity Press; 2012.
Two books describing Hitler’s encounter with Ott are Ross P. 1924: The Year That Made Hitler. Little, Brown and Company; 2016; and Simms B. Hitler. Penguin Books Ltd; 2019.