Is there an STD that causes a bad taste in the back of your throat? For two weeks now, I have had the most foul, nasty taste in the back of my throat coupled with lots of phlegm . For the first week, there was no soreness, only a really nasty taste...almost like a septic tank smells. Then for 2-4 days I had a very dry/ sore throat and a stuffy nose. Now the soreness and dryness is gone, but the disgusting taste is still there, as well as the phlegm. I m scared it might be an std because I preformed oral sex on a partner who I suspect may be having very...risky sex with other people.