Arm is heavy and numb following breast augmentation and mastopexy, no idea what's going on?

I had breast augmentation and mastopexy a fortnight ago and ever since the surgery my left arm has been experiencing heaviness and numbness, almost like circulation has been cut off - like a dead arm. It comes and goes but I have no idea what this could be. I mentioned it to my surgeon but he just said to keep an eye on it and he wasn't sure what it could be. It also gets worse in the evening. Has anyone heard of this issue?!

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