Lung pain

Hello Dr.

I am 30 years old  and have been smoking a pack for about 10 years.
Recently I have been experiencing some lung pain. It is like swithcing on and off an bulb. Comes for a second and goes. Not very severely painful but happen for a few minutes these days and does worry me. Also I feel bottom of my chest (left side) being sucked from inside.. As if something has stuck to it.

I am trying hard to quit smoking.Please tell me if this symptoms indicate something severe?

Thanks a lot!