Have you had any actual genital to genital sex with anyone in this time frame?
It's possible, but really unlikely to get hsv2 from oral sex. The next time you get a sore, if there is a next time, get it cultured within 24-72 hours of it appearing, and see what that says.
An IgG value of greater than 5 is usually high enough to not be a false positive, especially since you have symptoms. Where did you get the test done - was it through your doctor or at a place like STDCheck or LetsGetChecked?