What is causing the immense pain in my surgery site 2.5 years after giant lipoma removal?

I had a giant lipoma (the size of a softball cut in half) next to my left shoulder blade removed in Nov. 2016. Since then, I experience sharp stabbing pain starting at the incision site that triggers my entire mid-thoracic area, chest and abdomen to lock up, become tight and cause nausea. It feels like I am being compressed. The only relief I find is applying extreme pressure to my scar. Surgeon said there is no scar tissue or regeneration. It happens almost daily, multiple times a day.