What Causes Painful Dark Spot Near Belly Button Piercing?

I ve had my belly button pierced for 9 months now and recently I ve got a dark spot beside the top ball but about an inch away from the piercing there is a spot that is very painful to the touch ! I ve got tested for and infection and there s nothing there and I ve tried everything to fix it , I ve been working out more lately too so maybe it s the mussels in my belly doing something ?? I d like to know what this pain is and what can I do to fix it