upper chest spasms

hi again, i forgot to give a little background of myself.  I am 5'5 and 135 pounds. Quit smoking 4 months ago.  Got a raving review on my last physical (three weeks ago) - I used to suffer from anxiety but that has died down considerably.  I am not thinking this is anxiety related as I do not feel any pressure or anxiety or stress usually when I get the spasms.  I did have them a couple of months ago for a couple of days but they went away.  My doc had told me at the time, let's say about 3 years ago, that it was costochondritis.  No tests were done to establish this, only a physical examination, ie, putting pressure on my chest cavity.
Hope this clarifies matters a bit.  I await any reply that will help!
Thanks!!!