back and lung pain?

I am 31 year old male. and have slight asthma ( do not take meds regularly ). I have never smoked. Recently, about a week ago, I started to experience pain in my upper left back ( in between my shoulder and spine ), and pain when breathing deeply, also when I yawn. Today I started to notice my sternum is sore as well and the pain has become a little more constant. Any idea's what this could be? Your help is greatly appreciated

[Victoireh]

Along with this pain, due you get any asthma symptoms like shortness of breath, tight chest, cough or wheezing on a regular basis? This could mean your asthma is not in control and needs some action to be taken.

The other thing is you could be over breathing. Do you yawn a lot to try to get more "air" in? This can be brought on by anxiety/stress.

I was also going to suggest a pulled muscle, but since you say you are having soreness from back to front, I don't think it's likely.

Otherwise, go see your doctor who can run some tests and give you the help you need.