DEAR DR. ROACH: I have a dry cough that’s been going on for about 13-14 years. I’m a healthy 62-year-old and read that it is called “cough variant asthma.” I would like to know more about this but can’t really find anything about it, except that it will eventually get worse if it’s not treated. I was checked twice in the past 15 years for asthma, and I wasn’t diagnosed. However, I’ve not been diag…