OK I have a three month old greman shepherd, Tuesday she was happy, playing outside with us and even playing football with my two kids, then yesterday morning I let her loose and she came in the house and I give her a little bit of her food and she turn it down, she never touch her food at all, she mainly laid around all day yesterday but she did drink some water yesterday and last night and today she ate a small piece of a hamburger from last night supper then after that she will not eat anything but she did drink some water today and this evening, I just offer her a little bit of can dog food and she has not ate any of it yet. Please any suggust will help

The only wright answer will be from your vet

I agree with the vet visit. When a dog is refusing to eat there is something amiss.
Thee are lots of things that could be going on.
Has she been properly vaccinated and dewormed up to this point?

I also agree with the vet visit.

The only guess I could make is that she has an upset stomach. I'm basing that on the fact that you obviously offer table scraps. Dogs can't handle different foods easily. It takes time for them to adjust to different food. In fact, if you choose to change dog food it has to be done gradually, otherwise the dog, especially a puppy, will get an upset stomach.

She took the hamburger, so that would suggest that she's not sick, she's willing to eat, she just doesn't want her food.

What are you feeding her? Is she peeing regularly and pooing?

Still, this is just a guess, and a vet really is your only option.

Parvo?