Hi Cressida - I had pneumonia after chemo, also. It's not unusual. But it all eventaully cleared up. Unless you don't trust your doctor - and if you don't, best to find a new one, because you'll be with him/her for a good long time- then I'd trust what (s)he says. I think it would be incredibly unusual for lung cancer, which isn't the most common place for breast cancer to metastasize, to develop SO soon after treatment, and become large enough to see. My advice? If your doctor isn't recommending any further tests, then you probably don't need any. (S)he'll probably get you X-rayed again somewhere down the road to see how that patch looks, but in the meantime - I'd go forward with a positive outlook and try to stop worrying. Or, if you can't stop worrying -  ask for a second opinion, which is always an option. Good luck - PJH