Hi welcome to Health care magic forum. The dark marks on the lips of your daughter aged 1year 8months of age appears to be due to drug reaction like sulpha
drugs, if she used it prior to this. Dark marks on the tongue are suggestive of worms in the stomach. Instead of tongue and mucous membrane
it would have appeared on the lips. Don't worry they could be not more than that.Stools examination will reveal the presence or abscence of the worms in the intestine.
I advise you to consult a dermatologist
, for diagnosis and treatment. With a non invasive treatment it can be cleared completely.
Wishing for a quick recovery and thanks for calling.