Issue covid vaccine

While waiting during the 15 minute observation after receiving the covid 19 Pfizer vaccine, about 10 mins in, my body started to get weak, I was cold and sweating, I could feel my body feeling like it was shutting down, vomited. I watched my blood oxygen levels lower on the pulse oximeter. After about 5 mins I started to feel normal again. Please note this is something I have experienced many times throughout my life but did the vaccine maybe triggered it as it was a bit more intense than other times. Could it have just been my nerves? I experienced no other pre-vaccine symptoms besides a slight headache which I think might be because the lowered oxygen levels and a slightly sore arm. I made it thru that dose but I’m now scared what might happen when I go for my second 😩