10 yr old daughter usually has very large stool. Few days now with diarrhea but no pain in tummy. Having many accidents. Could be obstruction related?

Possibly. If only few days and no pain, not likely a serious problem, perhaps a viral enteritis--which would normally resolve within a week. But many accidents makes me wonder about severe bowel irritability, perhaps something is making her anxious. If there is an impending obstruction, yes, watery stool can get around the blockage. Talk things out fully with her. Then check with family doc/pediatrician.