My chest hurts all the time and I feel as if I don't get enough oxygen. Please help.?

I used to be a very active person until this problem started when I was about 8yrs old. At first it was only if I was playing hard ie: running a lot, riding around on my bike aggressively etc. I was told I had acute asthma but the meds did absolutely nothing to help. As I got older it got worse. I never stopped complaining about it especially since I was very active. I loved exercising, running, biking, and what not. By the time I was 15 I would be out of breath just from walking up the stairs from the first floor to the 2nd floor of my high school. If I had been running or moving about excessively no matter how many deep breaths I took I could not make the pain stop and I'd still be gasping for air and my tongue would begin to feel like it was swelling and throbbing. No matter how much air I took in I felt like my body wasn't getting the oxygen or something. When I was a junior in high school I joined the track team because it was always a pion of mine to run despite my problem. I was a hurdler and a sprinter and after I would compete hard in a race I would practically collapse on the ground for 30 min or more trying to make my breathing stabilize. And one terrifying day the inhaler I was prescribed made the episode worse. My heart was beating so hard and painfully and my tongue throbbed so hard and felt so swollen that it felt cold and ached so much I kept biting down on it to try and curb the pain. I thought I was going to die. I demanded my mom take me to the dr and not accept their asthma diagnosis. They ran some asthma related lung tests and said my lungs were completely healthy and I was asthma free. That was not comforting at all. That was the extent of what they did. They sent me home saying I was perfectly healthy. At that point taking a deep breath was only slightly discomforting. But it got worse. I'm now 24 and I can't walk to the kitchen w/o having some breathing struggles. Now the pain is constant in my chest and a deep breath is painful and not relaxing at all. Sometimes taking a large deep breath results in a cough as if I just took a deep breath near chlorine. Best way I can describe it. I've become extremely out of shape and often feel like I might have heart problems. But after years of seeing Dr after Dr and nothing being done to figure it out I tire of them looking at me like I'm crazy. This whole thing is very depressing especially since I have a 4yo who I can't keep up with and a very under exercised dog. People call me lazy and they have no idea how bad I wanna just go out and run or ride a bike with no problems. It's terrifying because it just gets worse as the years go by. I don't know what tests to ask the dr for or where to lead them with my problem. At one point I thought it might be anxiety, but it just doesn't seem to fit since it has been a progression from when I was a child. I just want to be healthy amd I don't know where to turn. I really hope that someone can help point me in a direction that might lead me to an answer. I would like to add that I'm a woman and I'm not a smoker, I drink rarely, and I'm not a drug user. Please any help would be appreciated.