What Causes Nausea And Dizziness In A Lung Cancer Patient?

I am a 68 year old woman and a retired teacher. It has been 7 years since my lung cancer diagnosis. I have had all of the usual treatments, I did not tolerate the chemo and radiation, and stopped treatments before they were done. I get scanned regularly, and each scan shows stability or improvement. I have been using cannabis only for 2 years. My question is about a problem I have been having with nausea (sometimes vomiting). There is a dizzy feeling in my head when I am nauseated, so it helps if I just sit and rest. When I have cannabis in my system, (I can elaborate if needed) I feel normal most of the time. I have shortness of breath due to 2 surgeries to remove tumors that took my upper right lobe and a chunk out of the left side as well. I have been told I also have COPD, but I do not have a productive cough and I only get out of breath when I exert myself.