Hi & welcome....I would not recommend giving her a bath quite yet...she is very small yet and not quite at the age of full bathing yet...you can freshen her up some if you would like, also I use J&J baby shampoo on my pups when it is bath time, I feel that if it is good to use on babies and also tearless, it must be pure enough for puppies. Also getting her of Science Diet it a plus, not very good food...you might mix a little of the SD in with the new food you put her on to help with a poo poo situation. Just keep a close eye on her with her being that young and small without her mama, I am sure you and her will be just fine.
Jackson
Gracie
Tucker
Rosey
Abigayle