Hi I'm A Teenager That's Been Sexually Active For About

hi I'm a teenager that's been sexually active for about a year. I've been on birth control for 10 months and last week me and my boyfriend had sex and it's made my vagina opening swollen and I've had a weird thick brown discharge. I've also felt very sick to my stomach but I haven't eaten anything weird recently. and it can't be an std because neither me or my boyfriend have ever slept with anyone else.