How do you know if you have asthma?

So I've been swimmin for a while now, but recently I've been having a sore throat and chest pains. I feel out of breath during practices that have never been hard for me before. And when we do simple sprinting sets, I start wheezing. It's really loud cause while I'm wheezing above water people underwater hear it. No one in my family has had asthma, so do I have it? Also how do they test you for asthma?