Your hsv2 IgG is quite likely a false positive test, as evidence by the negative reflex. You also wouldn't get hsv2 from oral sex, but would get hsv1 genitally.
Five seconds of oral sex is highly unlikely to result in any STD. Oral sex is far less likely to result in STD transmission than vaginal or anal sex, especially when it's so brief.
Maybe you were mildly dehydrated and your water and cranberry juice fixed that. You might have had a mild UTI.
The swollen gland - if it is swollen, we are so bad at determining our own swollen glands - wouldn't be from this. You might have a swollen gland in your groin, but not in your neck. If you are concerned about that, see your doctor.