This may be a bit too much detail for some but it's part and parcel of asthma.
When you develop the 'cough' and can actually cough up and spit it out, what colour is it?
I am asking as this morning, I was coughing up tar (for those that don't know, I smoke / did) and you can normally tell the difference as it's a browny colour and lumpy. I also coughed up blood this morning, nowt much but atleast 3 times, could tell by the colour and taste (YUK!)
And, because, when I do have an attack and I get a cough, it's stickier than superglue and is normally white / slightly greeny/brown.