So it was definitely nitrite
Thanks everyone for the responses and kind words.
Final thoughts on this post in response to comments / questions before I put this behind me.
- It was definitely SodiumNitrite 99.89% that I bought, it did test positive for nitrites. I think it was too diluted and I threw up too much of it. Checking I can see it is no longer available where I got it, which was a foreign website.
- The taste & smell were not awful, they were just not pleasant. I think when you know you are taking something bad, your mind tells you it is worse than it is
- The paramedics injected something into me in the ambulance but I was not aware enough to ask / know what it was. I doubt it was MethB as I remember saying I didn't take anything when they asked and I didn't leave anything out that would have alerted anyone to it.
- I don't know what they tested for in the blood. I had hypoxemia, I was on oxygen and had a oxygen monitor on. They might have just tested the oxygen level in blood. It was the NHS so I'm not sure they test for anything they don't have to.
- In terms of recovery, after sleeping a few days, I'm fine - still tired, get out of breath easy and sometimes I'm dizzy but nothing major.
I don't have much time alone as everyone wants to make sure I'm ok and are concerned I'll have another "seizure".
I'm just putting this behind me and looking forward. If I get some time to myself next month, I'll probably try again with a much more concentrated solution and more antiemetics (spread out over 2 days).