Could just be a bug bite i cause its only in that one spot i would just wipe it with alil but of alcohol and keep an eye on it. Dont put anything on it and maybe a beenie so she doesnt touch it

It looks like she may have just scratched herself, and the skin is a little irritated. Or, it could even be an ingrown hair or an aggravated hair follicle. What I would do? Don't put anything on it, no lotions or soaps. If it's the same, or worse in the morning, then I would just call my/her doctors office. They have a "care line", and you can ask questions regarding your baby. Run it by them. If they feel like she should be seen, then they will get her in. But, unless she's acting like its hurting or bothering her, there is no real need to worry yourself until morning when you can get a better look. ❤️😊

Can you take another picture, in the light, without the flash of the camera?

I would get that checked out immediately!