Feeling light-headed every now and then (Asthma & GERD)

Hello, this is my very first post here. I am a 27 year old male, height 179 cm weight 81 kgs, and I have asthma since i was a child, and I have been doing the insanity workout for some time (heart rate is always up, and i burn almost 500-600 calories in 50 mins on average). After 3 weeks or so I noticed that, when I'm extremely tires, I was facing some issues like just sitting down watching tv and out of no where i gasp for air and feel my heart racing, but that only happened twice and only when i was feeling really tired. With that feeling I had a slight discomfort in my chest on the left side, it wasn't pain it was just a feeling that goes away when i burp. I stopped insanity for about a month and I was feeling fine. I also play football 2-3 times a week. Then, about a week ago I travelled and the day I travelled my heart rate was a bit higher than usual because I am not fond of airplanes, I stayed there for just 2 days and came back. Because it was a long flight, I felt quite tired. The day after I got back, I did insanity again, and this time my heart was pumping really fast and I felt I needed a lot of air because I was constantly stopping and breathing hard, but I continued. And ever since that day, I wasn't feeling "normal"..

I rested the whole day but I felt my heart still racing, the next day I played football. I felt fine during football, but about an hour after the game I took some deep breaths and then I felt that I was going to faint. Felt dizzy so I panicked and my heart started racing. Since then, i constantly feel light headed when playing or whatever, so I went and took a blood test and thankfully everything was normal. I usually had difficulty breathing, like losing the way I normally breathe which causes me to panic, so I try and calm myself down, but see that I was not quite comfortable with the way I was breathing. So I went to the doctor after that and told him my story, and he told me that I had Gastroesophageal reflux disease. He gave me a list of what not to eat, and told me to rest. He also told me to take Pariet twice a day, and gave me medication for my asthma. I rested about a week, then the next I started jogging lightly and all was good, I was even breathing normally and the lightheadedness was almost gone, or at least I don't remember having issues... until yesterday, I played football after resting for 2 weeks and saw that I was feeling light headed while playing.. So I panicked just a bit and felt my heart pounding. Whenever I panic I lose my way of breathing normally and so causes me to panic even more, but only for a few seconds, in a few minutes I'm back breathing normally. I continued playing a bit more thinking that it'll go away, but no it didnt. I read that this may happen because of GERD but I want to know what do I have to do to make it stop? I never used to feel this way, and I'm quite an active person. So please advise.