What Do Dark Green Tongue And Stools With Dry Scalp In An Infant Suggest?

My daughter, age 8 weeks, has had a dark green almost black looking tongue for 3 weeks now. Her stools are also the same color. No medications have been given. I changed her formula at 3 weeks of age and at 5 weeks, they symptoms arose. She s fussy, vomits more than normal but has steady weight gain and is constantly moving. Dry scalp that looks like dandruff. Can you help? Her pediatrician, who has been practicing for 30 years, is dumbfounded. HELP!