Ketamine Treatment

I was wondering if anyone has had an experience with Ketamine. My doctor has just prescribed the nasal spray for me to use, but only at times when nothing else seems to help with my pain. The doctor told me to be certain that I am either laying down or sitting, as I will get very light-headed and dizzy. I am to spray once in one nostril only, and this should help to calm my symptoms down for a period of 3-4 hours. We had discussed the coma treatments, as well as the IV, but he does not want to go that route at this point, basically due to my sensitivity to medications. I can't imagine that I would ever want to be placed in a coma! The nasal spray has to be made specifically for me, as pharmacies do not carry this drug. 

I would appreciate it if anyone could let me know their experiences with this medication, as I am a bit nervous right now.

Thank you in advance, and have a wonderful day!

Stacie