My dog won't eat his food.

So, the other day my German Shepherd hurt his leg, and he wasn't feeling the best. I can tell he was hurting and just didn't want to eat at all. Well now I can tell he's feeling better by the way he's acting. His leg still hurts him a little bit. But I noticed he won't eat his food. We would literally have to shove it down his throat so he would get a full stomach. Sounds bad, but I really needed him to eat. Same with water, he wouldn't drink. He would eat ice cubes instead. Well I bought him some new food thinking he just didn't like the taste of his previous food. He won't touch his new food. But he'll want human food. Before he got sick he would eat his food and would get human food every now and then. What can I do to get him to eat his food? He has a vet appointment monday. But I need him to eat before then. Like I said he's not sick anymore and he's perfectly fine besides his leg. I just can't get him to eat!