Welcome to the Forum. I'll be glad to comment. The exposure you describe was rather low risk as there are few STIs which a person can acquire from performing oral sex on another, if they were infected and most people are not infected. In addition, what you describe does not suggest STI to me. Most oral STIs such as gonorrhea are asymptomatic. As for herpes, if you had herpes, it would be expected that you would have mouth lesions as well as lesions within your mouth. Thrush is not an STI.
My suspicion is that this is some other, community acquired viral infection, not HSV, HIV or other STI. I suspect that it will go away with symptomatic treatment and would not be concerned. I would not worry. EWH
Thank you for your prompt response, It has helped put my mind at ease, you offer a great service through this forum for a topic such as this
Thanks again
P.S.
Its been 3 weeks since the event