similar experience with SIS?

So I had a Saline Sonogram which is the same concept as a hysterosalpingogram but they use saline and an ultra sound instead of dye and an X-ray machine. 
The procedure was very uncomfortable and at times painful but as soon as it was over I felt much better. Then boom ten minutes after the procedure I full on fainted and began vomiting and trembling with the worst pain I've ever experienced. I had this pain for 4 hours along with intense vomiting and bouts of fainting. 
The dr said this wasnt exactly a normal reaction but not a deeply concerning one and it was due to my uterus contracting to push out the fluid. She said it was similar to contractions that happen during child birth but...seriously?! it was JUST saline!!! How could it hurt that bad? 
Did anyone else have pain this bad or a similarly bad experience???? Please share I swear I feel crazy right now!!