I during an mri of my left knee I started having a real bad headache and My body felt like it was starting to?

shake and felt like i was going to wet my pants. just at that time the nurse said all done and told me i could go. I had a real bad headache, body felt weak and i couldn't swallow, nauseated, when i went to the bathroom to throw up as i held my head i felt i had a barret on, what is wrong with me. i felt like I was dying.did i do something to my body