Throbbing pain near mole?

I have this mole on my back just to the left of my neck and it's been there for as long as I can remember. I don't know when it started to change, but now it isn't so symmetrical and the mole is kind of all over the place. It's not very big, it's all the same color, it doesn't itch, it doesn't hurt, it's not scabbing, but it doesn't look like my other moles...the symmetry just isn't there.

I don't know if this is just me being paranoid, but I'm having this dull, throbbing sensation (I don't want to call it "pain" because it doesn't really hurt) near my left upper arm and near my collarbone on the left side. I'd like to think it could be a pinched nerve or something because I was doing some rigorous activity with my arms two days ago, but I'm not sure.

I'm going to go to a dermatologist soon, but any thoughts on what the throbbing could be would be greatly appreciated. Thanks!