Oral sex on women (cunnilingus) carries no known risk for HIV; no cases of HIV have ever been reported to be transmitted in that manner. And it's nearly zero risk for all other STDs as well. Having a dry mouth wouldn't make any difference. Even if your partner has HIV -- which is unlikely -- you were not at risk from this event, do not require testing, and can safely continue unprotected sex with a regular partner, if you have one. There also is no need for testing for other STDs.
Note that MedHelp permits a maximum of 2 questions every 6 months on the professionally moderated forums (see Terms and Conditions). The purpose is to prevent domination of forums by repetative and anxiety-driven questions about low risk events. Don't risk your non-refundable posting fee on a question before mid-September that would be deleted without reply.
Regards-- HHH, MD