Hi, my 2 year old daughter has had very dark black hard stools for two days. I have also noticed that she has not required much diaper change during the day for the past week, I change her diaper about 3 times a day only. And, have noticed that she is drinking fluids throughout the day. Should I be worried or let it pass? Her appetite is the same, nothing has changed in her, just the diapers and stool. Thanks!