B.W.
Have you talked to anyone at daycare about this?
My children all went to daycare, and two of them had to move from the family home where they were being babysat to a daycare home with a bunch of kids because the mom in the family broke her arm and couldn't care for them. They didn't exhibit any of those behaviors due to an increased number of children.
I suspect it may have something to do with learning a behavior from one particular child. ?? Then again, it may be something new. Before you start blaming, you need to ask some open and honest questions.
Talk to the daycare provider. Tell her that you've noticed this new behavior and it's come on kind of suddenly. Does he do it there, too? How does SHE handle it ? Do any of the other kids behave like that? Work as a team to handle his behavior the same way, so that the parenting people in his life are consistent in reinforcing good behavior and trying to mold his poor behavior into a more practical and useful response to something that bothers him.
Your son is 2. He is at an age where he wants to become more autonomous, and he wants what HE wants, not what you want, every once in a while. He doesn't have a supply of words yet to express himself, so when he doesn't get what he wants, he expresses it physically. When he gets frustrated and angry, talk with him. Give him words. Are you angry because I took the toy away? Did you want to keep playing with the toy? You may have the toy when you settle down and agree to play nicely with it. Whatever the issue is. Help him to learn to use words to express himself, even when expressing anger, because that will help him to move from using unacceptable behavior to using words to solve his problems.
It'll take a while. He isn't going to change overnight. But, by age 3, he will have gained new territory in his maturational quest, and he'll be "consolidating his position" instead of pushing for "more space". At age 4, he'll start reaching out again, and so it goes -- the even years tend to be pushing, exploring, and fiesty years, and the odd ones tend to be more calm. These are stages. Be sure of that. You aren't raising a monster. You need to be there to handle the problems, and enjoy the successes of each developmental stage, and help him through them, but know that he's working through his own growth, and it's frustrating for him, too.