Thanks for your query.
Sometimes calcium and iron supplementation causes acute gastritis
I suggest you to take her to pediatrician
for re evaluation as she may need some antiemetic.
Stop supplementation for few days.
For weight gain ,give her proper diet which includes fruits,boiled vegetables.rice porridge with curd,
milk with biscuits .Frequent and small meals are to be given.
Child takes some time to develop taste to different food items.You have to be patient with him.
Wishing your baby good health.