i noticed a bubble like thing a few weeks ago on my back with a few smaller bubbles around my left shoulder on my back and today i was kinda concernd about it so i had a friend pop it and a little bug came out, it looked like a shrimp, it was about the size of a dime the color was whiteish grey...i just want to know what it was and how i got it, and if its bad for me?

any help is appreciated thanks