Does this only happen when she has a cold? My 4-year-old son vomits when he has a lot of sinus drainage into his stomach. He has been treated with rectal phenergan suppositories, which almost always help. They make him very drowsy; they relax the muscle to prevent retching. If the suppositories are not working at home, then they might not be inserted far enough or are not staying inserted long enough. I know from experience, it is very difficult! My son feels like he needs to have a bowel movement and wants to immediately sit on the toilet, and there goes the medicine....I would talk to her pediatrician too, he/she needs to do whatever it takes to figure out what is causing the vomiting. Hope this helps.