Talk to Pulmonologist / Lung on Breathing Problem

My sister is suffering from breathing problem for 4 days. 4 days ago she had so much vomiting and after some time suddenly collapsed, we took her to the nearby hospital. Oxygen is given to her, all test were carried out ( ECG, CBC Profile, Lipid Profile, FBS ) all reports are normal, Still she is suffering from breathing problem, we took her to TABBA heart proper first aid is given and we were asked to take her to Pulmonologist, and he suggested these medicines (Deprel(50mg), Calcipan-T ) . But there is no improvement in her health. At least 5 times she has taken to the hospital to provide oxygen. The doctor asked us to neublize her if it happens again in the middle of the night. We don't know what to do, as when this happens she is so helpless, we are so worried please suggest what test should be carried out to check what's the problem? To whom we should consult now? Please tell me the best doctor for this problem.