So weird, I answered this and don’t know where the answer went.
False positive HSV PCR’s are rare but happen. Have you actually seen the result? If not, I would ask for a copy to be certain this is what you think it is.
If the western blot is negative for HSV 2, I think you should rely upon it as your situation did not present a risk for HSV 2.
I think the amount of Valtrex that you’ve taken should not interfere with the western blot
Do you mean what creates a false positive PCR?