Question Regarding my 4 Year Old Daughter

HV,
My daughter has about 3-4 white spots on her face. Around the cheek aread, she has a wheatish complexion so they are rather noticeable. She has in the past had problems with constipation, but now we are forcing her to drink more water, which has helped allot. The spots are a different shade of her natural skin color, no scarring or blistering either, just white in appearance. We were shopping at the mall the other day, and a lady at the store said she has worms or parasites. I wanted to get your opinion. Do you think she is deficient in nutrients or could she possibly have worms. She is average height and weight. She sleeps fine, but like I said has had problems with constipation. We don't feed the best of food either, I am partial to blame as well. Please let me know of your thoughts. Thanks...I can provide any other info you might need...