Hello Lucyblue,
I received my apple watch on Thursday last week, and I am noticing the same thing. I got the stainless steel with milanese loop. I ordered a sports band and am going to see if that helps, but I am really bummed. I love the watch and all of the features. I just can't figure out what is causing the pain in my arm. By the end of the day, my entire forearm aches.
Just for information: I am wearing the device properly, almost to the point of being too loose, and in the proper location above my wrist. I notice the pain mostly when I'm at rest. The watch causes pain, and also causes my muscles to twitch.
I am in fairly good shape, and I thought it would be fun to use the activity features on the watch.
My husband and I are both in the medical field, so I do have a basic understanding of diseases and causes of hand/arm pain. I have been looking online for ANY explanation for this pain. So far, I haven't come up with anything, which is really, really frustrating. I do not have an allergy to any of the materials. My skin looks just fine - no redness or bumps. My husband, I'm pretty sure, thinks I'm nuts, and I am trying to convince myself that I am. However, every time I put on the watch, I am noticing the pain. I even took the watch off and did similar wrist and hand movements, to mimic the use of the watch.
A search online of pain in fitbit users revealed problems with pain on that device as well, which makes me wonder if somehow the heart rate monitor has something to do with it, but I do not see how that could be?
Does anyone know what might be going on? I really want to keep and use the watch. It is so awesome, I'd hate to have to return it.