Shortness of breath

30(m) looking for some advice. Occasionally since I was a young teen, a couple of times a year I go through bouts where I have shortness of breath that hangs around for several weeks before disappearing. I’ve had blood tests, urine tests, chest X-rays, oxygen test, EKGs etc. I’ve been told my lungs sound normal, no inflammation, blood levels are normal all that good stuff and my heart is good. Just wondering if anyone has gone through this and what the issue was.