toddler not gaining weight

My daughter 2 and has not broke 22lbs. Today we had a weight check following 3 months of doing pediasure. She has not gained any weight. Today her pediatrician drew blood to check for some underlying issues. The one is the most concerning was ciliac disease(gluten allergy). Has any other mommies had to deal with if so how did you adjust to the change? Just looking for advise to learn more about this while waiting for the test results from the dr.