As people have mentioned this is casued by one of the sensors in the watch. It can be HR or the wirless charging. I have tried fitbit Versa and now Galaxy watch 2 and had issues with both. If you dont care about heart rate sensor then you can do what I did which is to cover the bottom of the with paper and tape. I added multiple layers of tape to make sure it blocks off everything. So far I have not had any pain since then. Watch still tracks my steps and can charge without any issues. it just does not track heart rate, which I am willing to give up. Hope this helps.
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