Can you lose any job opportunity confiding in occupational medicine specialty?

Yes. An occupational medicine physician wears different hats. Depending on what they do, they may have a duty to inform your employer of safety risks that you may pose to yourself and others due to certain medical conditions that you have. For example, if you have a cdl and you develop diabetes and take insulin, and the occ med doc finds out, they are required to inform your employer of this.
It depends. One of the roles of an occupational medicine specialist is to evaluate people for their physical conditions. If someone has a condition that would make it unsafe to perform the essential duties of a job the doctor will give the employer advise on how to modify the job to fit the limitations of the employee. If those limitations can't be matched to the job the person may not be hired.