Agreed that the OP should get checked out by the GP. Even though my asthma isn't really a problem any more, I still have the blue inhaler on my prescription list and I am called in every couple of years for a review. Best practice seems to change over time, so an up-to-date opinion wouldn't hurt.
It's a more serious condition than many people think. Mention of 'life-threatening' reminded me of the time I put the kids to bed and then spent the rest of the evening putting polyurethane varnish on a hardwood staircase. After I had finished, I got a beer and sat relaxing for a while in the same room. Within 15 minutes I had an attack so bad my wife called out the doctor, who was there in minutes. For a short while I thought I was finished, as I simply couldn't get any air into my lungs and my vision was starting to go. One adrenaline injection in the butt, and within ten minutes I was fine, but it was very scary. Forty years riding fast motorbikes, and the closest I come to checking out was while doing a bit of home improvement!