Hello,
Most experts agree with the fact that chlamydia is not know to be transmitted that way.
Oral sex exposes you to gonorrhea, herpes and syphilis. £ weeks after the encounter is a good moment to test for gonorrhea, but maybe a test for the other two is not accurate.
For syphilis, you can test 6 weeks after the encounter, and if you get it negative, you can repeat it 3 months after the encounter, as there a people that take longer to show a positive result.
For herpes you can test 3 months after the exposure.
But the general risk is really low.
All the best.
DragonPulse.