Seems very plausible, thanks. Mine was only a half of a circle and not at all jagged. I'll have to investigate further.
I've had a history of debilitating allergy headaches, feeling once or twice as if death was near. I have even been close to death after experiencing a bad case of listeria. However, nothing has ever come close to resembling the effects of this experience. As you said, it's freaky. I would have almost thought someone spiked my food with LSD.