I want to hear your thoughts and advice on dealing with bully situations.

So DS is 2 years 5 months old. We recently signed up for a summer soccer class for a total of 5 sessions. He was the youngest and the smallest in the class. The class was for 2.5-3.5 years old, I was told. We weren't even supposed to be in this class, but the young 2 year old class was all sold out and we were placed in this group.

DS wasn't able to follow instructions as closely as the older kids were, and I suppose the older/bigger boys think he's weird. Toward the middle of the class when they were doing a soccer match, a big boy pushed DS down and he fell on the ground crying. Coaches didn't see what happened and no one did anything. DS was doing so well the entire class until that point. He ran back to us crying, and wouldn't return until much later. Then after he finally returned, this same boy went to the coach and accused DS that he bit another boy! (I didn't personally hear him but husband claimed he did). DS wouldn't bite anyone, that's just something that he doesn't do. I mean come on, he was the freaking smallest in the class he was scared/confused half the time how would he even bite anyone?

Personally I didn't want to step in as the "grown up" in all of these situations (and today we really couldn't, they were in the middle of a match but both coaches didn't see what happened. I didn't want to create a scene). I want to teach DS how to deal with these situations on his own. Unfortunately DS still couldn't really talk clearly so he couldn't really talk back to these bigger boys yet. But this is probably going to happen again in the future. Not just with this class, but with other older, bigger kids in other scenarios.

What would you do? What works for you? I just wish he could talk clearly and I would have had more options.