** 1. as the name suggests hypersensitivity pneumonitis [HP] i.e. hypersensitive reaction to an antigen which you have inhaled [pigeon in your case] PS. A lymphocyte proliferation test can be done if you are suspecting an antigen that cause it. 2. because, it is Hypersensitivity, thus main stay of any treatment will be AVOIDANCE of ANTIGEN i.e. dust,mould,fungi or any non specific stimuli. PS. Influenza and pneumococcal vaccines are strongly advocated . Breathing Exercises to clear lungs of inflammatory products. . Frequent position change, chest physiotherapy and incentive spirometry should be done 3. Ayurveda Drugs which acts as Immuno modulators like Ashwagandha, Guduchi, Trifla, Shatavari, SHIRISH (Albizia lebeeck) can be given. 4. development of fibrosis implies that HP has converted into chronicity, for that along with medicines, Oxygen and Pulmonary Rehabilitation will be needed. 5.Consult with your Physician about future Modalities and Medicines.