Sounds like you need a trip to the GYN, girl. Yes, it could be an STD or STI or a vaginal infection like BV or a yeast infection. Any kind of recurring soreness, stinging, burning or the sort of pain you're decribing is reason to not pass go, not collect $200 and get to your gynecologist or sexual health clinic.
When you're there, do be sure to be honest about being both sexually active and having had unprotected sexual intercourse (or other unprotected activities).
Your other symptoms may or may not be raleted -- but do bear in minnd that having one infection or illness taxes your immune system and makes you more prone to get others. So, for instance, if you have an STI, you're more likely to catch a common cold than you would be otherwise.
Editor and Founder, Scarleteen
My epitaph should read: "She worked herself into this ground."
-- Kay Bailey Hutchinson