Your chances of an std are small, but it is possible.
Have you talked to the girl to see if she has been tested? If you do talk to her, do not accuse her of having something - simply say you are wondering about stds, and thought maybe you should talk about it. If she says she has been tested and is fine, then let it go.
If you are concerned, go to your doc or a clinic and get tested. Your chances for HIV are very very small. Most people don't have HIV, and the chances of you getting it from a female