2 1/2 months old cane corso wont eat :( please help?

We just took a baby cane corso and she wont eat. I tried purina, pedigree, belcando, and an other one don't remember the name and she just turns her nose at it. she eats barely 200 gr of food daily and she should eat up to 750 gr :(.I even tried the food she is used eating Brit and nothing. The guy(first owner) said that she is probably under stress still(we separated her from her mother,father and sisters :( ) and that eventually she will start eating. You can see that she is hungry bit she just doesn't wanna eat. It's been almost a week now and i still can't get her to eat :(. Please anyone give me some advice, anyone had the same problem? Please please help :S