Chlamydia

Ok question for everyone. How do I know if I have chlamydia without going to a dr first? I just recently had intercourse with an ex of mine and didn't remember until after we had sex that he had a 3 some with someone that I know that actually does have chlamydia. Idk if it's a mental thing I'm having right now but idk what the symptoms are and they all range but I just don't feel as comfortable down there as I usually do.