A lot of people seem to be under the impression that a sex crime is the sort of thing that only a pedophile or some other kind of creep is going to be accused of doing. While it is true that some of the most perverse elements of our society are going to be considered sex offenders, the category of sex crimes is often considered to be quite broad and it was meant to be this way because of the fact that it was intended to be a consequence for people that stepped out of line in a way that was not deemed acceptable by a court of law and they are thus going to be punished for it accordingly.
If you want an example of how broad sex crime can be, just look at nineteen year olds that go out with seventeen year olds. These people are widely known to be just normal kids that are in relationships with people that are a couple years younger than them. However, in the eyes of the law a nineteen year old that is in some kind of a relationship with a seventeen year old is going to be a criminal, and there is a good question that the nineteen year old in question is going to end up being prosecuted in some way which is definitely not something that they are going to appreciate very much at all if you think about it for some pretty obvious reasons all in all.
If you are a teenager that has been accused of a sex crime, you need to find a lawyer that specifically handles sex crimes. These are the only people that would be willing to help you and will have the knowledge required to do so.