 [ Symptoms ] i have found a large hard lump on the right side of my groin [ Disease ] your boyfriend may be not be telling the truth chlamydia is caused by exposure to someone else that has chlamydia simple as that going from anal to vaginal sex can cause a severe bacterial infection from pathogens that live in the colon this is not a safe sexual practice both you and your boyfriend need to be carefully tested since chlamydia is often accompanied by other stds word to the wise use condoms with this guy and other guys too