An hour later, I ended up in the emergency room and was admitted for a couple of hours with an IV drip and inhalation treatment. Damn, it was the worst experience I've ever had. Fainting spells followed one after another with severe hyperventilation, leading to shortness of breath.
I was allowed to go home after a couple of hours; all tests were good except for the lactic acid build-up in my muscles due to hyperventilation, for which I received the IV drip. The inhalation also worked wonders, and today, a day later, I'm as happy as a clam again.