If you’re sexually active, sexually transmitted diseased are a possibility. Your partner doesn’t have to be hiding anything from you, they can be transmitted even if he/she doesn’t know anything is wrong.
Here’s advice from Luke Adams, a sexual health counselor:
The window for gonorrhea to show up is 2-6 days. The window for chalmydia to show up is 1-5 days. Syphilis is a tricky SOB, and can remain hidden up to 12 weeks or so. Consequently, it pays to be tested about a week after a big event.
If anything comes up, get immediate treatment. If anybody tells you that they have even had an exposure to syphillis, you ought to get immediate testing and immediate treatment (DO NOT WAIT TO GET TREATMENT if you’ve been told you’ve been exposed).
Then, the standard sexually transmitted diseases testing that sexual health counselors recommend for anybody who is sexually active is every 3 months (monthly for sex workers). Usually, clinicians will ask that, if you have been treated, you get a re-test two weeks afterward as a test of cure.
By “testing” we generally mean tests for gonococcus and chlamydia (urine test, and anal and oral swabs), and blood tests for T. Pallidum (syphilis). We also urge regular testing for Hepatitis C. If the person is HIV-negative and sexually active, we hope they are on PrEP and getting their regular battery of HIV viral load tests and STI tests quarterly. If the person is HIV+, we hope they are getting the same, and are on ART (anti-retroviral treatment) which also serves, when the virus is suppressed, as TasP (treatment as prevention).
Again, we always advise immunizations: against Hepatitis A and B, against Meningicoccus, and against HPV, for all of which there are vaccines, as there are for flu and pneumococcal pneumonia.
Suppressive treatment (daily acyclovir or valacyclovir) can suppress viral shedding and reduce (but not remove) the risk of the spread of herpes (which most sexually active men who have sex with men carry).
Treatment for HCV is now very effective at cure in many cases, though very expensive.
We have the technology to minimise the impact of sexually transmitted diseases; arm yourselves.