Did you touch any? I've read before someone making the same remarks and how they felt they breathe it in somehow and then felt some of the symptoms (fast heart rate, queasy upset stomach, headache, etc). Now don't take my 100% word on this but if I remember I remember them saying they didn't choose to go to the hospital and ended up feeling better. BUT I don't know the timeframe. If you feel light headed and your about to faint and also keep feeling the other symptoms for the next 10-15 mins then I'd consider calling but it's up to you.
I remember reading how 1-5 grams can kill a person so if you actually feel you've accidentally poisoned yourself then you should seek medical assistance. If you call remember all you have to say is that you ACCIDENTALLY POISONED yourself and that the SN is used for CURING MEAT. I repeat do NOT mention anything about suicide unless you want to go to a psych ward.
Edit: how strong do you feel dizzy? How does it compare to your average anxiety if you have anxiety?