Proper Dog Nutrition??

My dog eats bits of things off of the floor and I think it's because she's not getting the proper nutrition. She used to eat Purina Beneful Original but I switched her to Purina Beneful Healthy Harvest a few weeks ago and her behavior is still the same. Please help, I don't want her to ingest something harmful and end up paying $2,500 I don't have for the removal surgery.