Welcome to the forum. Oral herpes isn't an STD, so this is a borderline topic for this forum, so my replies are brief. For a more detailed response, you might consider posting a question on the herpes forum.
Your symptoms sound typical for oral herpes and a dermatologist's diagnosis of oral herpes is very reliable. Almost all oral herpes is caused by HSV-1. And the HSV-1 blood test misses around 20% of infected people -- so your negative test result doesn't change anything.
It is also possible you acquired the infection recently, and that a repeat blood test would be positive in a few weeks. If it's a new infection, it seems unlikely you caught it from a kiss on the ear; your lips where the ulcers are had to come into contact with the virus.
In any case, this doesn't sound serious. However, if you develop recurrent oral outbreaks in the future, you can speak with your doctor about a possible prescription for treatment to help prevent outbreaks or to treat them promptly when they start.
I hope this helps. Best wishes-- HHH, MD
Very thoughtful response, thank you
On one level, if an infection is acquired through sexual activity, the person with the infection of course may consider it an STD. On the other hand, the world at large doesn't consider oral herpes, or any infection caught by kissing, an STD. And in general, people don't look at persons with lip sores that look like oral herpes and think "That guy's got an STD." Even if he happened to have acquired the infection by oral sex (which is rare), it wouldn't generally be viewed as an STD, regardless of how that particular individual thought of his infection.
As another illustration, oral herpes isn't addressed in the STD treatment guidelines issued by CDC, WHO, or the Canadian and British STD recommendations, regardless of how it was caught.
Thank you for your quick response. Just a curious question, if someone contracts HSV1 or HSV2 from giving oral sex, isn't that considered and STD? It's not the case here, just couldn't help asking based on your response