I'm having the exact same problem with a 42mm SS watch with the Milanese Loop. Aches and pains in the arm the watch is on. It's not too tight as I can fit 2 fingers under the ML.
My Wife has a bracelet that's supposed to help with Jet Lag. It has 2 reasonably strong magnets on it and I get exactly the same problem - dull aches and pain in the arm and hand it's worn on.
I've just switched back to a White Sports Band. So far, so good.