How could shortness of breath/trouble breathing be a collateral affect from a benzo?

May be anxiety. . The sensation of shortness of breath, or a sense of air hunger may be due to anxiety. I'll presume you are being treated for that, since you are taking a benzodiazepine. If you are taking too large a dose or combining it with alcohol, then yes, could cause respiratory depression. But there are many causes of sob in 49 y/o male, such as heart or lung problems, so should be checked by your pcp.