How exactly was the pneumonia covered up when she wasn't diagnosed until yesterday? Unless you think her doctor is just lying.
As stated above, she was diagnosed with pneumonia on Friday, not Sunday.
She and her campaign chose to cover it up. It became impossible to hide any further when she had to leave the 9/11 services early on Sunday, and after a video showed she wasn't stable enough to get into a vehicle on her own without falling down.
They were forced to reveal the fact she has pneumonia, they didn't choose to do it on their own accord.
You're using an absurd definition of "covered up." Did she lie to the press about having pneumonia? Why in the world would she have needed to disclose the fact that she had pneumonia to anyone? What duty is she under to tell you when she gets a cold?