Crackle heard in lung

Hi all. This is my first post, I have suffered health anxiety for many years and I am currently very worried about my lungs.
I had a mild head cold 2 weeks ago. Then 10 days ago I developed a bubbly popping noise in my upper chest when breathing out. I contacted my gp and had some antibiotics (prescribed over the phone, my chest was not listened to at that time). I took a 7 day course of antibiotics but by now I was no better and my cough was worse.
I went back to my gp who says he could hear inspiratory crackles in my right lower lung, he took bloods but this shows all my infection markers and inflammation markers to be normal. He has requested a chest xray.
I am now really worried about things like lung cancer. I am a 40 year old female, healthy, no other problems. Never smoked.
Has anyone else had anything like this which just cleared up over time? Or should I be worried ? Many thanks