I’m sorry that you’re feeling so bad andI understand to some degree because I’m also a survivor of lung cancer and I had my upper left lobe removed in August of 2020. I read that you had your surgery last October and it’s really not so long ago, it was a very big operation and can take a year or more for you to feel like your old self, the surgery changes us from who we were to our new self. I felt the tightness around my chest but I felt it was normal and I had it checked out to eliminate any problems. I have gained weight in my belly at times and I found that it made the tightness in my chest worse, our stomach also gets bigger inside and can put pressure on the diaphragm, it’s very good that you had it checked out to be sure…I don’t know why you’re gaining weight, did this happen without you changing your eating habits, if so then I’m not sure why this happened. I also thought perhaps it’s gas but this can be explained by the doctor. I hope that you will feel better over time and find the answers to this issue, good luck with your progress.