Hello. Thank you for your query at DoctorSpring.com.
I understand your concern and will do my best to help you.
If your doctor has told that what you have is a recent infection, then the most probable way you would have contracted is through your partner. If he has tested negative, then an uncommon possibility exists if you have had oral cold sores earlier. Cold sores are caused by HSV1(Herpes Simplex Virus type1). HSV1 can rarely lead to genital herpes by auto-inoculation(self transmission). In this case you will have positive blood test for HSV1. Has this test been done for you?
The chances of your partner developing a new herpes infection after that exposure is about 50 %.
If you could upload all the your and your partner's test results, it would be very helpful and I could get a much clearer picture.