I don't have an answer but I wanted to let you know that you are not alone. My 2 almost 3 yr old throws fits too and tries to hurt himself too. I think that its for attention and to see how far he can push you.
My son is 15 months, and is just entering the "testing me" stage. When I tell him "No", he will throw himself on the floor and most of the time he hits his head and cries. I felt really bad at first but once I stopped making a big deal about it and cuddling him when he hit his head, he stopped doing it so much.