Occupational Asthma
The condition you describe is most likely asthma. In any case, it should be treated as asthma. Many people who have an underlying propensity to develop asthma experience the start of the chronic condition following some provocative event, such as a viral infection or inhalation of any of a host of irritants that cause coughing or wheezing. It is probable that your asthmatic condition would have apppeared sooner or later even in the absence of the exposure to formaldehyde.