Anyone have any bad experience using this patch? My question is, I was reading up on the patch and it says that it's a "topical" patch but then it goes on to say that a small amount absorbs into the blood stream. How does that happen if it's topical? Does this really work? I have shoulder pain and I am thinking about trying this patch but I'm kind of leary about it and the side effects. Anyone suffer side effects with this? Thanks and have a great holiday!