Is it asthma? Or... what is it?

Hey...
I've been researching this problem, but never got the answer. I want to know if I have asthma or not, whether I should use the inhaler or not. Since I've been joining track, I don't know why, but in the middle, like after 50 meters or less, I start to get out of air, my heart beats SUPER FAST suddenly, and when I finish my distance, it's a LITTLE hard to breathe. I was NEVER like that, it's only been recently. Is this asthma? Oh AND, I get confused whether to breathe through my mouth or through my nose, because nose is hard, like I can't get enough air, and mouth, it's using too much of my energy and breath.

HELP!

P.S. I was born with asthma, but it wasn't serious, I never needed to go to the hospital or anything like that.

SHOULD I USE AN INHALER?

You have to work up to distance running. And having been born with asthma you'll have to check with your doctor to get an inhaler. But don't expect it to increase your endurance or anything like that. It doesn't work like that.
There are many long distance runners out there that are asthmatic so don't let it stop you.
About the nose breathing who the hell ever told you you have to breathe through your nose during or after exercising? That's just not true. Your mouth is an accessory organ of breathing used in times of oxygen deficit and the need for deeper faster breathing. This in through the nose out through the mouth stuff is for yoga and as a breathing exercise for COPD patients.
They've tried to pull that stuff with me when I'm having difficulty breathing and I tell them to go out, run around the block and breath through your nose and see how it feels. It makes them feel better because they're at least trying. They also tell me to slow my breathing down by breathing in through my nose and out through my mouth. Don't they think that's what I'd like to be able to do more than anything?
Sorry about the ranting. But it's things like that that give kids like you difficulty.
God bless.

i have that problem im 13 but your abdomen muscles is what helps you breath it could be that to or its your asthma getting worse go to an asthma doctor they will do this breathing test you breath in hold your breath and stuff or they hook you up to a treadmill and you walk than it gets faster