I almost died from getting high? What was it?

Ok so recently me, & my two buddies went into these woods and were supposed to be smoking marijuana, we did it with a bong and many times i would let the smoke feel up to my head and then i would exhale, after smoking for a good minute i felt dizzy and holded on to a fence suddenly i sat down and i felt like i was in a dream so i felt both of my friends and didnt feel anything i felt like i was touching air, so i got kinda scared and started 2 walk home but then all of a sudden i asked them to walk me home cause i forgot where i lived, so they were taking me and i fell in the middle of the street and never got up cause i couldnt feel my legs, i started getting paranoid and couldnt stop talking and i had two outbursts. After a while i was shaking a little and i was turning purple, i couldnt really breath so much and when the ambulance arrived i couldnt even hear the sirens cause i just couldnt hear well i felt like everything was far. They ran tests at the hospital and it tested negative for Marijuana, Cocaine, Meth etc. and they said it was a drug but they have no clue what drug it was. So Does anyone know what kinda drug it was? a friend told me it could have been opium