It’s always hard to say what’s going on with flu like symptoms, especially in flu season. Yes, it could have been from first infection.
He needs an IgG antibody test and yes, I think he waited long enough from his last contact.
I would encourage him to get a copy of his herpes testing so you can see what was actually done and what kind of herpes test was used.
He wants an IgG type specific antibody test.
If his previous test was actually an IgG antibody test and was negative and is now positive, he could have acquired this from you. What was the date of his last testing?
It is possible that you acquired it from your husband or another partner. Did you have sex with anyone prior to your husband?
I’m afraid if your last partner tests negative you will not be able to know when you actually got infected. And if he is positive, I’m afraid you won’t be able to know with certainty who infected whom.