Hi there Cynthia. If the history provided by you is 100% accurate, then you have absolutely nothing to fear. Aquiring STD's from changing rooms or pools is extremely rare & far fetched in today's world & toilet seat infection (while possible) does not necessarily classify as an STD & certainly syphilis
cannot be aquired in this manner assuming you have no abrasions or cuts on the surfaces of your body in contact with such fomites. Paranoia
or Venereophobia though needs to be assessed by a competent psychologist
& addressed as it may progress further if not checked. For my part, i would like to again reassure you that you DO NOT have an STD but do please meet up with a counsellor or psychologist near you for further help. Do hope have allayed your fears & Good Luck for the future.
Dr Praveen Rodrigues MD Dermatologist
, Cosmetologist & Venreologist, Bangalore, India