Shallow breathing, sore airways & lungs, as well as heart palpitations....help!

[will44715]

I'm in my early 40's, and apart from very mild asthma occasionally when I have a chest infection (not a regular occurrence), I don't use inhalers or have issues.
Ever since a visit to my parent's place at Christmas, my breathing has been slightly tight, although it's not been a real issue, and I've not needed to take anything for it.
Around a month ago, my breathing became noticeably shallow, along with some lung/airway discomfort. It's continued, and I've had spirography tests, which suggest my breathing is within the parameters of 'normal'.
Interestingly, when they tested the blue Ventolin inhaler on me, it had negligible effect, which is worrying.
The doctor has given me a brown preventer inhaler, which only seems to be making my airway soreness worse, and possibly breathing more shallow. I have a chest scan booked for a week's time.
However, I'm concerned that my breathing is steadily becoming worse. I have to walk more slowly and puff when i talk. Not ideal - I'm a teacher.
I also worry that the brown steroid inhaler is making things worse - the fact the spirography tests suggested the Ventolin inhaler wasn't having an impact is a concern to me.
Any suggestions of what else may be causing this pain, shallow breath and heart palpitations? I've looked up pneumonia, but it doesn't seem to fit - I don't have any 'wheezing' and I'm not coughing up any phlegm.
Any advice appreciated - it's affecting my quality of life, and the doctor seems utterly useless!