My kitty went from sweet and loving to wild?

About 2 weeks ago I found a kitten under a car. I brought her back home and moved with her to Florida last Sunday. She was very loving and would always come to us so we can give her a little scratch and purr when we did. Well awhile back I bought this play stick. I'm not sure what they're called but it's a stick with a string and at the end of the string is a big ball of feathers. She would never play with it at first but slowly started playing with it. Now she's become wild! She pounces at everything. She even pounces at our faces. When I go to pick her up she runs away. She never purrs when I pet her it's just such a drastic change. For awhile I thought it was because of the toy but isn't it natural for cats to play with those types of toys? Am I doing something wrong?