The symptoms you describe do not sound like any STD and definitely not herpes. That the oral lesions didn't go away on their own, and didnn't improve on a higher dose of Valtrex, proves they aren't herpes. Conceivably you are having some sort of allergic reaction or chemical irritation--but I cannot tell, and I also cannot tell whether it is related to your oral sex experiences.
I don't understand why you are embarrassed to tell your GP about your sexual activities. There is nothing special about oral sex today; it is understood by everybody, including your GP, to be a normal, regular form of sexual expression among healthy people.
Sorry I can't be more helpful. But the good news is that you have no worries about herpes (or any other STD) as the cause.
Good luck-- HHH, MD