In young, sexually active women, STDs--especially chlamydia and gonorrhea--are at or
tcy (e.g., an impending miscarriage
), fibroid tumors, and others. Injury during sex, including your partner's fingers, is not a likely cause.
Bottom line: Get examined soon, to include pelvic exam, pap smear, and tests for gonorrhea and chlamydia. It would be a good idea for your partner to get checked out at the same time.