My daughter is 12 years old and is complaining about pain in her lower right side of her stomach. She is also throwing up. The thing is she is on her period and I don't know if she feels this way cause of her period or is it something else. She started her period in January and felt the same way but her whole stomach hurt not just her right. After that month her period was normal a few cramps but that was it. Should I take her to the ER or can it just be her period?

It could be appendicitis or something else. I'd take her to the ER.