I'm very sad to hear about the cancer

That is a major bumber. I can't address your health issues and I shouldn't suggest that you smoke or vape anything in your situation, but I will tell you I enjoy my e-cigarette and after being a smoker for 15 years and now being smoke free for 2 years this is my experience.
First off, you really don't have to spend a ton of money, the e-cigarette I use is affordable and it does the job, take a look:
buy electronic cigarettes When I started vaping rather than using tobacco the first thing I noticed was that in just a week, I did not have chest pain anymore, I did not cough or have difficulty breathing when I woke up in the morning. I did not have tons of flem throughout the day. And frankly it tastes far better. I have converted my parents and my best friend to e-cigs and they are happy. I assume I could quit anytime I wanted to at this point, but I really do not see the point for myself, I enjoy vaping and it does not make me feel awful like tobacco cigarettes did. I am playing football a lot more and loving life.
I really hope you beat the cancer, Look into cutting your PH level a lot of alternative medicine specialists swear by it.
All The Best.!