Excercise induced asthma?

[Nells26]

Loooong story, I'll try keep it brief. Up until this year I have been a fit, healthy and happy female (currently 42). In January my husband told me my snoring was getting very bad - so bad that he has to wear ear plugs. I had a sleep test and I have very mild apnea - in that I only stop breathing once an hour on average but when I do its up to a minute and my heart races and oxygen levels drop.
I work out 3 times a week - plus do the odd 5km weekend run. I noticed around the same time just how puffed out I was getting. I can still work out but I need to take more breaks and I have to breath really hard and out loud to keep up with the work out. I recently did my usual 5km run and for the first time ever at the end of the race I was breathing crackly which was almost I'd say a wheeze.
In the meantime my chest feels continually tight and crampy - I had an ECG all good, a stress test on my heart which was also all good and they even check for a PE with a CT scan - all good. Due to have a heart echo next month.
Anyway in the meantime by late afternoon my chest hurts, it's so tight and I may have sharp pains or a continual cramp. When I breathe in it's tight. I suddenly had a thought today could it possibly be respiratory rather then heart (which is what I was thinking it could be). I get out of breath easily (which is unusual because I consider myself fit with a spin class, boxing class and circuit class all in one week) and this could be from walking outside to feed the dog or got to the post box - it's not extreme but I am certainly puffing and I am having to breathe embarrassingly loud and heavily during my fitness classes....
I have a mild cough - in that it's barely present, just in mornings a wee bit congested but more dry in the afternoon.
Anyone else experienced anything similar? Thanks.