About three weeks ago, I had unprotected sex. For about a week now, my vagina has been very irritated and itchy. Today, it has not been a problem,at all, like all the irritation went away. A few minutes ago, I wiped and saw a little blood, but shortly after, I noticed the blood was only coming from the left side of my clitoris. Yesterday, I shaved, and I had a burning sensation while urinating only twice after I had shaved. Could this be an STD? Or a yeast infection?