The White House is struggling on Monday to show that it has a burgeoning public health and political crisis under control as President Trump enters his third day of aggressive and experimental treatment for the coronavirus. Trump fueled the growing alarm with a publicity stunt on Sunday evening, leaving his hospital suite to drive by boisterous supporters who gathered outside the military hospital in Bethesda, Md., where he has been hospitalized since Friday for COVID-19. His doctors have said he could be released on Monday. But they have also admitted that their public statements have been optimistic, aimed at bolstering the spirits of their patient. Inconsistencies between medical briefings and White House statements have added to confusion and concern — combined with the refusal by the White House to lay out all the facts about when and how they learned a pandemic that has killed more than 200,000 Americans had entered the grounds of one of the most protected complexes in the world.