Wait, when did it mention that he hates doctors and hospitals? *interested* I don't remember that, I think my brain melted trying to explain that big clusterfuck up there
I want to say he mentioned it late in S1 or on "Zoo York". I know Behind Blue Eyes has it listed as a Flack Factoid.
Yes, it could very well be because of somebody he cared for, my crackworld notwithstanding. For all we know, Mama Flack died because of hospital negligence. "Who made you God, huh?" sounds very much like a doctor decided someone he loved was not worth saving at some point...