H8 Iam 62 Yrs Old Male With Restricted Breathing Under

H8 Iam 62 yrs old male with restricted breathing under exercise It is diagnosed as Pulimnary fibrosis but my doctor is saying its to an allergic reaction so they want to do a second biopsy to look for the trigger
My question What is main difference between fibrosis caused by allergic reaction and fibrosis Thanks john