Symptoms of a sexually transmitted infection in the throat may not appear immediately after infection. It can take anywhere from 2 days to several weeks or months for symptoms to show up, depending on the specific infection. In some cases, irritation from oral sex can cause a sore throat that may resemble a cold or flu. If you are experiencing symptoms such as ulcers or fever, it is important to consult a healthcare provider for testing. It's always better to be cautious and get tested if there is any doubt, as some infections may not present any symptoms at all. You can find a testing center near you by searching online.