Hello, around the middle area of my right chest, the bone feels much bigger than the one on my left chest, do u know why this is?

I don't think this was there before, not 100% sure.

And also, for a few months now, I have been getting these weird 'sensations' in the middle of chest and because of this sensation I have to 'pull' it, and I do this by twisting left to right until (whatever it is) I pull and it feels like a band of strings being pulled. This is not painful either.

I am 20 years of age, not a 'heavy or regular' smoker, but I have smoked on occasions before, but that's about it.