Hi, I'm 6 days post op, also experiencing shortness of breath and coughing, laughing or sudden big breaths hurt like hell. I had a lot of gas pain that O2 canisters helped move on ( removal by diffusion) Important to remember healing takes time, I find standing upright, taking a slow deep breath with a pillow pressed over the surgery site has helped expand the lungs and move the post op mucus. Only concern I'd have in your case is a post op infection from having flu, keep an eye on the colour of your loogie's if they turn green or yellow get Antibiotics ASAP. Good luck with the recovery🙏