Asthma?

Curious as to if anyone has experience with this… I’ve always played sports and have never ever had asthma. I recently went to an allergist and found I have exercise-induced asthma(????). I genuinely thought for the past two years that as I upped my mileage, my breathing was just getting a little harder. I have an inhaler but my longer runs feel hard and I’m having to stop every half mile because I can’t breathe. The Texas heat and humidity could be making it worse, but either way I feel like my lungs are drowning. Wondering if anyone has any little tips or tricks or recommendations for how I should adjust my mileage each day. Any info helps! 🙂