You might want to check out an Apple 'Magic Trackpad' (there are Windows drivers as I think you're on a PC). I've previously used the 3M mouse you refer to as

You might want to check out an Apple 'Magic Trackpad' (there are Windows drivers as I think you're on a PC). I've previously used the 3M mouse you refer to as well as all manner of trackballs, larger mice, etc and nothing has done more to alleviate my mouse hand issues than the Magic Trackpad. I think this is mostly because it removes the need to clench your hand around anything and it can be much more relaxed, yet you still have very fine control (I regularly use it with Photoshop).