it seem your child have oral ulcers on tongue.
these are painfull and sore.check with ypur baby
for stomqch upset like gastiritis because ulcers usualy
occur due to high acid content.
i would advice you to apply anaethstic gel like hexagel
twice daily fir 5days for releif.
these ulcers will heal ifself in 5-6days does not require
any spl medication.
do maintain oral hygiene
,give short meals,if reguire
consult a gastrologist.