Okay please give me your best advice... All 3 of my children have been suffering from diarrhea with (I know its disgusting but hey, were all looking too be or in, the medical field here!

green, very smelly, runny stools. Up to twice and sometimes 3 times a day. It has lasted almost 2wks now and is JUST starting to look better. Thats it, no fever, no abdominal pain or dehydration. BUT I took my children to the er last Saturday night due to the fact I was AFRAID that it was the Rota Virus. My daughter weighed in at 21lbs. I had no questions about it nor did they address this issue so i didn't think twice. She is only 1yr and 6m. I was told to get some specimen samples and then proceed to give it to their pediatrician. Well luckily she had a wellness checkup this last Mon. At her wellness the nurse weighed her in at 19lbs. Thats 3more lbs than my 6m. old! But now that I look back,it dawned on me that I was holding her arms up to keep her steady on the scale. I FRIEKED. She is suppose to be triple her birth weight by 1. (8lbs 15oz at birth) She has always been small for her age but NEVER this small. Her diagnosis was Diarrhea and ANOREXIA. Well the grandparents came over and we weighed her again and again. 21lbs. Still very low but not as low as she had been weighing. She doesn't look anorexic but she is skinny. Well they tested the specimens and that of her other sister and brother and it came back neg. for the Rota Virus. They are still testing and I won't know the results until Fri. What in the world is going on? What could this be and do you think she was weighed wrong? Since then she had gained 1lb and we have been feeding her everything under the sun to get her weight back up. Cross your fingers everyone. Thank you!