WorriedUniStudent, It is vary rare to get an STD from anything but intercourse. The only other way is from oral sex when he has a certain type of cold sore on his lips (herpes).
It can be a normal reaction to the abuse from your very delicate parts due to the roughness. He might also have scratched you. It can also be a yeast infection either present or starting. Do you have any unusual discharge (chunky and cottage cheese like)? You can buy over the counter treatments from your local store or pharmacy for yeast. There are also some common itch relievers available from the tampon/pad/condom/pregnancy test/lubtricant isle in the store.
Some general hints: Do not wash with strong or scented soaps - preferably plain clean water, remember to wash under your clitoral hood, do not wash inside your vagina and do not douche, wear undies with cotton crotches to wick away moisture, use only unscented menstrual products and change it on schedule, always wipe from the front to the back to keep bacteria from your anus out of your vulva. Always make sure that whatever goes into your vulva and vagina is clean - fingers, toys, household object and penisis.
Lastly, please be very careful about what you do. You do not want to spoil your future because you are buzzed or horny. Make sure you have condoms ready. Even having Plan B ready for in case something goes wrong is a good idea. Do not ever allow yourself to be pressured into intercourse before you are ready. Using your brains instead of your hormones will save you a lot of hassles.
Please be careful!