Bc,
I don't like to post negative things, but my husband, definitely developed pneumonitis when he was on Alimta. He had good results as far as some shrinkage and then stability, but his breathing was progressively affected from early on. Even when he started having the pneumonitis , the pulmnologist thought it was a bacterial infection and gave him an antibiotic. His breathing was gradually worsening and then it became very bad almost over night. It was the CT scan that showed it as a ground glass pattern on the lung. High doses of prednisone are given for it , as well as using oxygen . The prednisone cleared the pneumonitis, but he was left not being able to breathe as well as he had before. I hope this isn't what is happening with you , but it is treatable and it is good to be aware that it can happen. Sure hope you get answers.
Sue