Don't think the worst. I can't even imagine any cause beyond irritation of some sort. I suggest seeing a dermatologist. If the swelling occurs before or between visits, a photograph may help. I've seen patients with intermittent swellings (penis, eye, etc.) that have neither specific cause nor much significance. As to why this began now, that may have no answer, but it's still unlikely to be anything of serious concern.
Best.
Dr. Rockoff