Welcome to the forum.
In general, oral sex is safe sex -- not completely free of STD risk, but much less chance of infection than vaginal or anal sex. And of oral sex exposures, probably the lowest risk of all is for the oral partner in cullilingus. That you "vomited up really thick yellow stuff" probably is irrelevant; that's obvously a gastrointestinal problem, not an STD symptom. No STD is likely to cause a lesion on the tongue, and I suspect your own suspicion is correct -- some anatomical variant. Among other things, no STD (really no infection of any kind) can start to cause symptoms in under 2-3 days. To the specific questions:
1) As a non-monogamous sexually active person, and given your anxieties, perhaps it is a good idea to visit an STD clinic or other provider to be checked out for STDs. But not because of this particular exposure and symptoms.
2) I doubt you caught any STD.
3) See above. Cunnilingus is not totally safe, but you probably could have exposures like this once a day for more than a year and never catch anything.
4) I have no orther advice, except to not worry too much about this. Get checked out if you're nervous, as suggested above -- but I doubt you caught anything.
Regards-- HHH, MD
Ok,
Thankyou very much,
Yes I got tested recently so everything in the past is ok.
I was really only worried about this particular incident but your response has calmed my mind significantly - So i guess from what you said just regarding this incident that it is not worth getting checked out.
Once again thankyou, and also thanks for the quick reply.