if you can, contact where you had your original lesion culture done to see if it was typed to know if it's hsv1 or hsv2. Odds are it's hsv1 if your blood test is negative. even the best blood tests we have still miss 1 out of every 10 hsv1 infections unfortunately.
anytime someone suspects you have a herpes lesion, ask for a lesion culture. if you are one of the small percentage of folks who don't test accurately on the herpes igg blood tests , it's the best way to confirm if indeed it is herpes and if it is, which type it is for more accurate answers.
grace
Are you in the US? It would be good to know what type of blood test you had; not all blood tests are reliable nowadays.
Anyway, as mistakeguy said, culture is rarely wrong and you should assume you have herpes. If you can, try to find out with your doctor if the culture was ever typed - type I or type II. And be seen within 48h for a lesion culture next time the sores appear in your foot.
The lesion culture is rarely wrong if it is it will be through human error.
If you had genital herpes it can be either type in that location. Though the virus does affect the nerves it can sometimes show up on the foot.
If you get symptoms be seen within 24-48hrs for a lesion culture.