So waiting to hear back from her on what is wrong with him...
He apparently said it felt like he did when he had food poisoning. We ate all the same things today except he had a baked potato at lunch and fries at dinner that I didn't have.
ETA: Well... he's doing okay for now. The initial tests all came back okay. The doctor decided to go ahead and admit him though and then do a stress test on him in the morning. Just to check that everything is okay. The doctor is leaning toward him pinching a nerve that caused his blood pressure to drop. My dad (like myself) has really low blood pressure to begin with, so it doesn't take much to make him pass