Thanks for the replies....
To answer the questions:
1. House is 4 years old and no ducts as no air con! Cleaned once a week though....
2. My little one has a permanent green runny nose.
3. Last year when I had it first the mucus was from deep in the throat and a nice green colour, a really sticky blob every morning
This time no real mucus once the cold had passed.
4. Wheezing comes on involuntary normally when slouching, lying, after a heavy meal or the occasional huge laughter session. I can do 30 min cardio, take my heart rate up to 160 and nothing.
5. Smoked when I was a student but that was over 20 years ago and only in the pub.
6. Slightly over weight, I was awakened this morning by it, no pain, just discomfort/tightening of the chest, light wheezing and a blocked nose which within minutes had turned into clear runny mucus. No back pain or orthopedic surgery. Did 30 min cardio with no symptoms.
Am off to the GP's this morning as we can't go directly to a specialist so will see what they say.
As an aside searching on here I've seen some people mention reflux as a cause. For the last two years I've had indigestion remedies in the bedroom as I lie in bed I occasionally (maybe once a week) get indigestion and occasionally get woken up by it and have to take a tablet.