Sternum / back and left shoulder pain please help

Hello all,

Looking for some advice on an on going problem of approx 1 year....

I have been experiencing very bad sternum pain its a little sore to touch but its not that that worries me... its not all the time but a few times a day at least as i move just normally like everyone does i get an extreme piercing pain feeling in my sternum in-between my breasts which makes me shout 'ouch' it sometimes resorts me to tears....
i visited my gp who asked if id been in a car accident to which i replied i have not (because i have not), he sent me for an xray BUT i never got the results hense why i think they must be ok?!, anyway i have kind of just put up with the pains but since my upper back has been hurting and my left shoulder blade....
I did 3 weeks ago have a chest infection and wheeze present was given amoxicilin it didnt work so was put on a different antibiotic which worked however tonight i feel preasure in my lungs... like im struggling inside to breathe somehow.... im not athsmatic....i do not smoke..... i do not heavy lift or work in a heavy active line of work....
I did have plurosy 2 years ago but the pains have never gone.... can someone please help me and provide me with some advice

thank you