I used to smoke as well--I quit 5 years ago. I was also scared of what I might have heard when I went to the pulmonologist. But, ultimately, I had to go anyway. You would not necessarily be sick (or feel sick) if mtx were affecting your lungs. The lung infection I had didn't make me feel sick at all--I had no fever, no fatigue, nothing--just a dry cough that got worse at night. And yet, it still scarred my lungs.
I would still recommend that you get it checked out anyway. Good information to know. Plus, when I got my evaluation done, my rheumy said it was excellent that now I had a very extensive work up on my lungs--more than most people get in a lifetime. So now, if anything were to happen to my lungs, I have a great baseline for comparison purposes.
Make the call anyway--worry about quitting smoking some other time. What you have going on could be absolutely nothing.
Current dx: Rheumatoid Arthritis
Suspected dx: UCTD/Early Lupus
Current Meds: Enbrel, Plaquenil, Aciphex, Ultracet, Zyrtec, Allavert-D, Zantac, Tylenol PM
Past Meds: Relafen, Vioxx, Mobic, Voltaren, Sulfasalazine, Entocort, Prednisone, Humira, Reglan