For what it's worth....I to once had been diagnosed with a std while both of us were totally monagamus! ...I also went to a hospital clinic for care as money was always tight & it was much more affordable. On one occaision I noticed after they finished one part of my exam they put that instrument that "opens up" the vagina for a pap smear into a "sink" & then they picked it back up & reinserted it in me before I had the presence of mind to proteset!
Even if they were using a disposable instrument on me, how many others were set down in that sink before being disposed of before mine was set in there & reinserted!!
To this day I strongly think that was the source of the std.....................possibly a similar proceedure caused this in your wife??