My Daughter Got A Cold About Four Days Ago. We

My daughter got a cold about four days ago. We did not gave her any medicine in the last four days. However, she is having fever and also complaining headache, dizziness, and fatigue. In addition, when she woke up from her nap she reported that color of things changed into either orange or yellow. She is 6 years old and I am very concerned. We sent her to her pediatrician this morning and was told that these symptoms may accounted by dehydration. However, I am not 100% sure. Any possible reasons for her symptom? What shall I do now?