were you both tested for std's prior to starting to have sex together?
if you already treated for chlamydia, no way to do confirmatory testing to confirm that it wasn't a false positive. since you have symptoms again, you need to be seen again and tested for yeast and bacterial infections vaginally.
since you are pregnant, make sure you both seek out type specific herpes igg blood testing too. odds are that neither of you were ever tested for herpes before and testing early into pregnancy to know your status is a good idea.
grace
He should be re tested . It is possible it didnt show . Where else would it of came from ? Are you sure he got tested ? They should of gave him the meditation to treat it even if his was negative because yours came back positive and youve slepttogether . If he didnt get treated you are passing it back and fourth .