She might be nervous if it's a new school.If not a new school.There might be someone picking on her and she doesn't know how to tell you.Plus it might also help me if I knew how old she is.I'm not wanting any problems either,I'm just a parent too.
I have this same problem every now & then... It usually occurs when I'm nervous or upset. If school is stressful, then that could also be why. I guess you could say your daughter's skin is performing like a mood ring would. I hope its nothing serious.