Ergonomic Mice

So yesterday I went to this electronics store waiting to buy a cool new mouse for laptops. While I was looking for a nice mouse, I have this really caught my eye Logitech V550. It looked good with the little usb. The price was a little high bu I said to myself, why buy something if you do not walk, to buy the right thing. So I bought him. When I got home I was so excited. I immediately needed. When I tried using it after a few hours, my hand hurt so bad I werent able to move it. I tried to give to my friends and they told me that this mouse is not ergonomic. I was crushed. I tried again and again, but my hand would not stop damage. My right ring and little fingers really hurt. So I decided to do some research on the internet but could not find anything. I do not know what to do. The store is only to take back, they have such a policy. It's really cool, but my hand really hurts!