These are not symptoms of any std.
Most likley chafing like you suspect
Hi, not having any outbreaks in this six month period is a good indicator you did not contact herpes from the brief oral. Extremely low risk activity.
Herpes is a tricky question because it can be spread through skin to skin contact. Since you have already get it tested, I don't think you have herpes. You are just being stressed out.
Yes, you are being over paranoid. 5 - 10 secs of contact was brief exposure, it is unlikely to transmit any stds. You need to pay less attention to your penis from now on.
Also. I have had no fever or flu like symptoms