Mt 6 yr old daughter had abdominal pain that came and went, diarrhea for 2 days and now had a clay colour almost whitish BM? Could it be just a virus

Possible. its possible, if her stools do not return to normal color and remain whitish, she needs to be checked for a blockage in bile absorption since bile is what gives the stool its color. SHe could have any number of conditions that are leading to white colored stools.
Mgt/workup. If your daughter has continued pain, fever or change in her stool color, I would recommend a follow up visit with your PCP. They may consider hepatitis/liver screening tests.
Possible virus. When there is rapid transit of stool through the intestines,normal pigment and absorption are abnormal causing lighter colored stools. However clay colored stools can be seen in biliary tract problems such as stones. Notify your pediatrician if clay colored stools persist especially in combination with brownish urine.