Probably after it was too late.
I don't think we do a good enough job in general of teaching people what things should be a sign that someone is in extremis, whether in the ER when discharging patients or even in general ed classes, like health class in high school.
He said mentions thinks like having trouble walking. He should have been back at the ER right then, which was like three weeks ago. By the time he is having trouble walking, his body isn't compensating well, either to dehydration or extreme pulmonary consolidation from the pneumonia.
It no doubt didn't help that ERs in LA (and most urban areas) are disaster areas and he probably didn't feel well enough to go there and wait 19 hours for help.