Only if you're a dude.
muscle spasms
Yes, that is the top of your rib cage.
It's caused by a conflictous situation. Solve the conflict and the lump will disappear.
I'm not sure about that, but in my opinion I think you should go get it checked out by your family doctor. It's better safe than sorry :) if you are going through pubery it is perfectly normal
No. It may be due to an infection in your reproductive system or elsewhere, but I would definitely see the Doc sooner rather than later.