Hello,
The culture being negative could be a few things.
1. The virus wasn't alive on the culture swab or there wasn't enough to grow it. The culture was taken to late and the virus died off. Or the other it wasn't HSV. The culture is more accurate if the lesision is swabbed no later than 48 hours after showing up.
2. What is the type of HSV it came back positive? Type 1 or Type 2. About half the adult us population has type 1 HSV as cold sores even if they can never remember having cold sores. Please give us your IGG values (IE: hsv-1 igg 2.85 hsv-2 igg 0.45). We can better guide you on what to do.
3. You can read my journal entry on the IGM and IGG differences at:
http://www.medhelp.org/user_journals/show/173049/Herpes-IgM-Testing?personal_page_id=991435
The easy way to explain it is IgM is not the best for use in adults with testing Herpes. IgM is a worthless test that crossreacts and is known to some other issues. So for Herpes we don't recommend it. IGG is the best and most accurate for Herpes.
Virial shedding is when the virus is active on the skin and there are no symptoms of an outbreak. Depending on the site of infection depends on the amount of virial shedding. For example HSV-1 genitial virial shedds less when compared to HSV-2 genitially.
I would say a good resource for you to read is the Herpes Handbook at www.westoverheights.com and you can get some great information on Herpes.