Chest pains with Asthma

Over the past year, I have been getting pains on my left side 'deep' under my breast and into my shoulder blade. I have had various tests, including bloods and an ECG and my heart is fine! My Asthma review was last week. My doctor listened to my chest whilst I breathed in deeply and she said she could hear congestion in my chest to start with, but then it went, so she said it was 'sticky' mucus that was gathering in my lungs but then 'moving around' and it was this that was causing the pain and inflammation. She said take both my inhalers whenever I felt the pain and that should help. The pain is worse at night, when I'm lying down and I often wake up in pain and every morning I have severe pain too. Always on the same side. Up to now, the pain has not subsided.

Does anyone else experience this pain? I'm told my asthma is only mild and I have only really ever suffered one attack as such. The most troublesome sympton for me is a tickly cough, which is now under control, so the pain can't be caused through coughing.