My 15yr old daughter told me when she went to the bathroom tonight there was blood & clots in her stool. her stomach has been hurting all day & nausea?

Potentially urgent: While there are many possible simple explanations for this story (heavy menses, hemorrhoids, etc.) GI bleeding can be sufficiently significant as to threaten life, and so without a good understanding of where it is coming from, how rapidly, etc. it is difficult to be sure it is safe to wait it out. I suggest an early evaluation.