sti!?!

so my vagina had been itchy so i shaved it and that some what fixed the problem but i’ve also had discharge for ages but i just thought it was normal ( white) but after my last fuck without a condom with my ex who was a virgin (about 3 weeks ago now) my discharge has been more white and thicker until yesterday my discharge was brown and i noticed there was like bumps around my vagina, so i did some research and i’m scared that it may be an sti. i’m not 16 yet and i feel uncomfortable going with my foster mum to the doctors to go get it checked out. i’m freaking out and very unsure on what to do