What Causes Dark Green,runny,sticky Stools?

Hi, my daughter is 18 months old and has had a runny nose for the past week or so. After a few days the clear mucus turned thicker and slightly yellow. She got a cough around that time, which seemed to be the peak of whatever whe was at. She had a fever at the very beginning. She has been pulling at her ears a little, although this is something she does when she is tired anyways, so I'm not sure if it may be/have been an ear infection. My question though is over the last two days her stool has been dark green, runny and sticky. what should I do (if anything at all)?