Welcome to HCM.
Fishy odor following sex contact suggests that you are still having Bacterial vaginosis
. It can be confirmed by vaginal smear test.
You consult your Gynecologist or a Genito-urinary physician. If the smear examination confirms the diagnosis they will help you to get it treated successfully with alternative antibiotics. It is better to have the treatment both of you together. Treatment for you alone the success rate is lower.
Get well soon.