Medical Student Syndrome
Medical Student Syndrome is an unusual affliction that affects people in medical training. The student reads about a novel disease, and finds they have some symptoms of this disease, and then imagine they have this disease.
Here's a brief audio account from NPR, entitled: "The Challenge of Knowing Too Much, and Too Little"
People with inexplicable skin conditions, or itching, or people who simply worry a lot about their health, might resort to performing research on the Internet. It seems quite reasonable that they might find Morgellons, and since the range of symptoms is very broad, they would recognize some symptoms. They would then decide they have Morgellons.
Not that their problems are imagined, if people are sick, then they are sick, they have real problems, physical and/or mental. They are not sick with "Morgellons" but they might be suffering from a recently discovered form of MSS known as Cyberchondria.