How often does this occur? Does it radiate to any other parts of the body? Do you experience it while laying down, sitting, walking, or running?
What part of the rib area? High? Low? Left or right sides? Back or front? Near the sternum?
You're 16 and male, so you should be growing like a weed now. Make sure you're getting lots of water and nutrition. Exercise, but go easy on the weight lifting. I've read that weight lifting during your teenage years can actually stunt your growth.
When you're having the pain, can you breathe? Do you feel like you have to hold your breath or the pain will get worse? Is it like a burning cramp you get after running for a while?
What you DID describe, sounds like a muscle spasm. I'm equating it to the chest cramps I used to get as a teenager... Increasing my water helped actually. And taking slow deep breaths when I felt it start.
Like I said the pains are completely random and last only 7-10 seconds. they stay mostly stay on the sides of my rib cage but they have gone to my back and stomach. And my doctor told me he was 100% positive that it wasn't anything related to growth because I have always been tall and never had a big growth spurt, and i am 6' 4" now.
Color me jealous about the height - I'm short.... and squat. :p
Sounds exactly like the muscle spasms I had as a teen... I still get them when I don't drink enough water.