I Was Recently Diagnosed With Invasive Lobular Breast Cancer On

I was recently diagnosed with invasive lobular breast cancer on the right side. I have had a lumpectomy and will start radiation next week. It was very small and a stage 2A. I am not sure if there is any correlation, but for the past month I have had a crackling like sound when lying on my left side. This doesn't occur right away when lying down, but when I wake up, I can hear it and it is worrisome to me. It was very loud at first but I did take antibiotics and then it lessened quite a bit. I do feel a bit more short of breath especially with exertion or climbing stairs. Dr. doesn't seem to be concerned or feel it is related to the breast cancer diagnosis. A MRI didn't show anything. Any ideas?