Is your son relatively new at being in this daycare? Was he used to being taken care of at home before? If he has been there since an infant, it is surprising that his behavior has morphed into this.
If he is new at this center, I think perhaps a smaller daycare might be in your best interests. If it's a smaller place, running around won't be such a big deal as to cause the teachers too much trouble. They just call to each other about getting him back into the room. Also, a different center may be better at having enough activities to hold his interest so that he doesn't feel he needs to run out of the room.
If your son is grabbing food, he might have trouble waiting to eat. Perhaps the teacher can get some food to him a little quicker to head that off.
I'm so sorry that they hit you with this right before your surgery. Will they not give you a chance to find another place before he has to leave?
Best of luck, especially with the surgery,