(uncountable) Molecular nitrogen (N2), a colorless, odorless gas at room temperature. (countable) A specific nitrogen within a chemical formula, or a specific isotope of nitrogen The two nitrogens are located next to one another on the ring.
An allergist specializes in allergies, asthma, and allergic asthma. Internist. An internist is a doctor who specializes in internal medicine -- the study of diseases in adults, particularly those related to internal organs -- and who has completed three years of training after medical school. Pediatrician.
A chest physician--a respiratory specialist. Sometimes called a Pulmonologist. These chaps might call in a cardiologist just to check that the heart rhythms are ok. And they also may consult with an Ear, Nose and Throat (ENT) specialist depending on what they find.