Hi, My Name Is Jack. Recently I Had A Foot

Hi, My name is Jack. Recently i had a foot injury and when the doctor was showing me xrays and going over the probly i felt very faint, like i wanted to throw up, and my body breaks out in a sweat. Today I went to the Dentist and the same thing happened when we were going over x rays and pictures. It has happened to me since I was a kid. Do you know the term for this and anyway I can stop it from happening?