Testicular cancer survivor having trouble making gains

I'm a 14yr stage 4 testicular cancer survivor having problems making gains. My diet is clean and I make sure I get enough protein, carbs, and healthy fats(try to anyway). I have low T and cortisol issues that I have a Dr  appt for on June 16. I had half my right lung removed because the cancer had spread and my Dr wants me doing cardio for 30 mins 5 days a week. Is it at all possible to put on lean muscle while stil pushing myself as hard as I possibly can and having to do this much cardio? Any help is greatly appreciated! Thanks Marc.