Could my doctor have missed trich when iwas tested for other stds?

four months ago i went to the doctor and was told i had chlamydia and gonorrhea. i was treated and so was my bf. we got rechecked and were cleared. now i went back to the doctor last week to get a papsmear and was told i now have trich. could it have been missed when i was checked for the stds or would i have had to have gotten it after ?