Can you tell me why this happened?

I had a breast vacuum biopsy with 3 lots of Anaesthetic, I felt the biopsy cuttings, the pain I felt was intense, after procedure my body went into shock and started fitting, I lost consciousness a lot off times, why would this be, I don't suffer from COPD, asthma or any breathing conditions, I don't smoke.

im confused why this happen can you help me understand this please?